WeixiangYan/CodeTransOcean huggingface dataset:
Task: Soundex

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>


static char code[128] = { 0 };
void add_code(const char *s, int c)
{
	while (*s) {
		code[(int)*s] = code[0x20 ^ (int)*s] = c;
		s++;
	}
}

void init()
{
	static const char *cls[] =
		{ "AEIOU", "", "BFPV", "CGJKQSXZ", "DT", "L", "MN", "R", 0};
	int i;
	for (i = 0; cls[i]; i++)
		add_code(cls[i], i - 1);
}


const char* soundex(const char *s)
{
	static char out[5];
	int c, prev, i;

	out[0] = out[4] = 0;
	if (!s || !*s) return out;

	out[0] = *s++;

	
	prev = code[(int)out[0]];
	for (i = 1; *s && i < 4; s++) {
		if ((c = code[(int)*s]) == prev) continue;

		if (c == -1) prev = 0;	
		else if (c > 0) {
			out[i++] = c + '0';
			prev = c;
		}
	}
	while (i < 4) out[i++] = '0';
	return out;
}

int main()
{
	int i;
	const char *sdx, *names[][2] = {
		{"Soundex",	"S532"},
		{"Example",	"E251"},
		{"Sownteks",	"S532"},
		{"Ekzampul",	"E251"},
		{"Euler",	"E460"},
		{"Gauss",	"G200"},
		{"Hilbert",	"H416"},
		{"Knuth",	"K530"},
		{"Lloyd",	"L300"},
		{"Lukasiewicz",	"L222"},
		{"Ellery",	"E460"},
		{"Ghosh",	"G200"},
		{"Heilbronn",	"H416"},
		{"Kant",	"K530"},
		{"Ladd",	"L300"},
		{"Lissajous",	"L222"},
		{"Wheaton",	"W350"},
		{"Burroughs",	"B620"},
		{"Burrows",	"B620"},
		{"O'Hara",	"O600"},
		{"Washington",	"W252"},
		{"Lee",		"L000"},
		{"Gutierrez",	"G362"},
		{"Pfister",	"P236"},
		{"Jackson",	"J250"},
		{"Tymczak",	"T522"},
		{"VanDeusen",	"V532"},
		{"Ashcraft",	"A261"},
		{0, 0}
	};

	init();

	puts("  Test name  Code  Got\n----------------------");
	for (i = 0; names[i][0]; i++) {
		sdx = soundex(names[i][0]);
		printf("%11s  %s  %s ", names[i][0], names[i][1], sdx);
		printf("%s\n", strcmp(sdx, names[i][1]) ? "not ok" : "ok");
	}

	return 0;
}
Task: Knuth's algorithm S

C: #include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

struct s_env {
    unsigned int n, i;
    size_t size;
    void *sample;
};

void s_of_n_init(struct s_env *s_env, size_t size, unsigned int n)
{
    s_env->i = 0;
    s_env->n = n;
    s_env->size = size;
    s_env->sample = malloc(n * size);
}

void sample_set_i(struct s_env *s_env, unsigned int i, void *item)
{
    memcpy(s_env->sample + i * s_env->size, item, s_env->size);
}

void *s_of_n(struct s_env *s_env, void *item)
{
    s_env->i++;
    if (s_env->i <= s_env->n)
        sample_set_i(s_env, s_env->i - 1, item);
    else if ((rand() % s_env->i) < s_env->n)
        sample_set_i(s_env, rand() % s_env->n, item);
    return s_env->sample;
}

int *test(unsigned int n, int *items_set, unsigned int num_items)
{
    int i;
    struct s_env s_env;
    s_of_n_init(&s_env, sizeof(items_set[0]), n);
    for (i = 0; i < num_items; i++) {
        s_of_n(&s_env, (void *) &items_set[i]);
    }
    return (int *)s_env.sample;
}

int main()
{
    unsigned int i, j;
    unsigned int n = 3;
    unsigned int num_items = 10;
    unsigned int *frequencies;
    int *items_set;
    srand(time(NULL));
    items_set = malloc(num_items * sizeof(int));
    frequencies = malloc(num_items * sizeof(int));
    for (i = 0; i < num_items; i++) {
        items_set[i] = i;
        frequencies[i] = 0;
    }
    for (i = 0; i < 100000; i++) {
        int *res = test(n, items_set, num_items);
        for (j = 0; j < n; j++) {
            frequencies[res[j]]++;
        }
	free(res);
    }
    for (i = 0; i < num_items; i++) {
        printf(" %d", frequencies[i]);
    }
    puts("");
    return 0;
}
Task: Return multiple values

C: #include<stdio.h>

typedef struct{
	int integer;
	float decimal;
	char letter;
	char string[100];
	double bigDecimal;
}Composite;

Composite example()
{
	Composite C = {1, 2.3, 'a', "Hello World", 45.678};
	return C;
}


int main()
{
	Composite C = example();

	printf("Values from a function returning a structure : { %d, %f, %c, %s, %f}\n", C.integer, C.decimal, C.letter, C.string, C.bigDecimal);

	return 0;
}
Task: Fractran

C: #include <stdio.h>
#include <stdlib.h>
#include <gmp.h>

typedef struct frac_s *frac;
struct frac_s {
	int n, d;
	frac next;
};

frac parse(char *s)
{
	int offset = 0;
	struct frac_s h = {0}, *p = &h;

	while (2 == sscanf(s, "%d/%d%n", &h.n, &h.d, &offset)) {
		s += offset;
		p = p->next = malloc(sizeof *p);
		*p = h;
		p->next = 0;
	}

	return h.next;
}

int run(int v, char *s)
{
	frac n, p = parse(s);
	mpz_t val;
	mpz_init_set_ui(val, v);

loop:	n = p;
	if (mpz_popcount(val) == 1)
		gmp_printf("\n[2^%d = %Zd]", mpz_scan1(val, 0), val);
	else
		gmp_printf(" %Zd", val);

	for (n = p; n; n = n->next) {
		
		if (!mpz_divisible_ui_p(val, n->d)) continue;

		mpz_divexact_ui(val, val, n->d);
		mpz_mul_ui(val, val, n->n);
		goto loop;
	}

	gmp_printf("\nhalt: %Zd has no divisors\n", val);

	mpz_clear(val);
	while (p) {
		n = p->next;
		free(p);
		p = n;
	}

	return 0;
}

int main(void)
{
	run(2,	"17/91 78/85 19/51 23/38 29/33 77/29 95/23 "
		"77/19 1/17 11/13 13/11 15/14 15/2 55/1");

	return 0;
}
Task: Substring_Top and tail

C: #include <string.h>
#include <stdlib.h>
#include <stdio.h>

int main( int argc, char ** argv ){
  const char * str_a = "knight";
  const char * str_b = "socks";
  const char * str_c = "brooms";

  char * new_a = malloc( strlen( str_a ) - 1 );
  char * new_b = malloc( strlen( str_b ) - 1 );
  char * new_c = malloc( strlen( str_c ) - 2 );

  strcpy( new_a, str_a + 1 );
  strncpy( new_b, str_b, strlen( str_b ) - 1 );
  strncpy( new_c, str_c + 1, strlen( str_c ) - 2 );

  printf( "%s\n%s\n%s\n", new_a, new_b, new_c );

  free( new_a );
  free( new_b );
  free( new_c );

  return 0;
}
Task: Boolean values

C: int a = 0;
int b = 1;
int c;
string str1 = "initialized string";
string str2; 

if (a) {puts("first test a is false");}         
if (b) {puts("second test b is true");}         
if (c) {puts("third test b is false");}         
if (!defined(c)) {puts("fourth test is true");} 
if (str1) {puts("fifth test str1 is true");}    
if (str2) {puts("sixth test str2 is false");}
Task: Bitmap_Histogram

C: typedef unsigned int histogram_t;
typedef histogram_t *histogram;

#define GET_LUM(IMG, X, Y) ( (IMG)->buf[ (Y) * (IMG)->width + (X)][0] )

histogram get_histogram(grayimage im);
luminance histogram_median(histogram h);
Task: Check input device is a terminal

C: #include <unistd.h>	
#include <stdio.h>	

int main(void)
{
	puts(isatty(fileno(stdin))
		? "stdin is tty"
		: "stdin is not tty");
	return 0;
}
Task: Wireworld

C: 
#define ANIMATE_VT100_POSIX
#include <stdio.h>
#include <string.h>
#ifdef ANIMATE_VT100_POSIX
#include <time.h>
#endif

char world_7x14[2][512] = {
  {
    "+-----------+\n"
    "|tH.........|\n"
    "|.   .      |\n"
    "|   ...     |\n"
    "|.   .      |\n"
    "|Ht.. ......|\n"
    "+-----------+\n"
  }
};

void next_world(const char *in, char *out, int w, int h)
{
  int i;

  for (i = 0; i < w*h; i++) {
    switch (in[i]) {
    case ' ': out[i] = ' '; break;
    case 't': out[i] = '.'; break;
    case 'H': out[i] = 't'; break;
    case '.': {
      int hc = (in[i-w-1] == 'H') + (in[i-w] == 'H') + (in[i-w+1] == 'H') +
               (in[i-1]   == 'H')                    + (in[i+1]   == 'H') +
               (in[i+w-1] == 'H') + (in[i+w] == 'H') + (in[i+w+1] == 'H');
      out[i] = (hc == 1 || hc == 2) ? 'H' : '.';
      break;
    }
    default:
      out[i] = in[i];
    }
  }
  out[i] = in[i];
}

int main()
{
  int f;

  for (f = 0; ; f = 1 - f) {
    puts(world_7x14[f]);
    next_world(world_7x14[f], world_7x14[1-f], 14, 7);
#ifdef ANIMATE_VT100_POSIX
    printf("\x1b[%dA", 8);
    printf("\x1b[%dD", 14);
    {
      static const struct timespec ts = { 0, 100000000 };
      nanosleep(&ts, 0);
    }
#endif
  }

  return 0;
}
Task: Terminal control_Inverse video

C: #include <stdio.h>

int main()
{
	printf("\033[7mReversed\033[m Normal\n");

	return 0;
}
Task: Ulam spiral (for primes)

C: #include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <math.h>

typedef uint32_t bitsieve;

unsigned sieve_check(bitsieve *b, const unsigned v)
{
    if ((v != 2 && !(v & 1)) || (v < 2))
        return 0;
    else
        return !(b[v >> 6] & (1 << (v >> 1 & 31)));
}

bitsieve* sieve(const unsigned v)
{
    unsigned i, j;
    bitsieve *b = calloc((v >> 6) + 1, sizeof(uint32_t));

    for (i = 3; i <= sqrt(v); i += 2)
        if (!(b[i >> 6] & (1 << (i >> 1 & 31))))
            for (j = i*i; j < v; j += (i << 1))
                b[j >> 6] |= (1 << (j >> 1 & 31));

    return b;
}

#define max(x,y) ((x) > (y) ? (x) : (y))


int ulam_get_map(int x, int y, int n)
{
    x -= (n - 1) / 2;
    y -= n / 2;

    int mx = abs(x), my = abs(y);
    int l = 2 * max(mx, my);
    int d = y >= x ? l * 3 + x + y : l - x - y;

    return pow(l - 1, 2) + d;
}


void output_ulam_spiral(int n, const char glyph)
{
    
    n -= n % 2 == 0 ? 1 : 0;

    const char *spaces = ".................";
    int mwidth = log10(n * n) + 1;

    bitsieve *b = sieve(n * n + 1);
    int x, y;

    for (x = 0; x < n; ++x) {
        for (y = 0; y < n; ++y) {
            int z = ulam_get_map(y, x, n);

            if (glyph == 0) {
                if (sieve_check(b, z))
                    printf("%*d ", mwidth, z);
                else
                    printf("%.*s ", mwidth, spaces);
            }
            else {
                printf("%c", sieve_check(b, z) ? glyph : spaces[0]);
            }
        }
        printf("\n");
    }

    free(b);
}

int main(int argc, char *argv[])
{
    const int n = argc < 2 ? 9 : atoi(argv[1]);

    output_ulam_spiral(n, 0);
    printf("\n");

    output_ulam_spiral(n, '#');
    printf("\n");

    return 0;
}
Task: Fibonacci word

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

void print_headings()
{
	printf("%2s", "N");
	printf(" %10s", "Length");
	printf(" %-20s", "Entropy");
	printf(" %-40s", "Word");
	printf("\n");
}

double calculate_entropy(int ones, int zeros)
{
	double result = 0;
	
	int total = ones + zeros;
	result -= (double) ones / total * log2((double) ones / total);
	result -= (double) zeros / total * log2((double) zeros / total);
	
	if (result != result) { 
		result = 0;
	}
	
	return result;
}

void print_entropy(char *word)
{
	int ones = 0;
	int zeros = 0;
	
	int i;
	for (i = 0; word[i]; i++) {
		char c = word[i];
		
		switch (c) {
			case '0':
				zeros++;
				break;
			case '1':
				ones++;
				break;
		}
	}
	
	double entropy = calculate_entropy(ones, zeros);
	printf(" %-20.18f", entropy);
}

void print_word(int n, char *word)
{
	printf("%2d", n);
	
	printf(" %10ld", strlen(word));
	
	print_entropy(word);
	
	if (n < 10) {
		printf(" %-40s", word);
	} else {
		printf(" %-40s", "...");
	}
	
	printf("\n");
}

int main(int argc, char *argv[])
{
	print_headings();
	
	char *last_word = malloc(2);
	strcpy(last_word, "1");
	
	char *current_word = malloc(2);
	strcpy(current_word, "0");
	
	print_word(1, last_word);
	int i;
	for (i = 2; i <= 37; i++) {
		print_word(i, current_word);
		
		char *next_word = malloc(strlen(current_word) + strlen(last_word) + 1);
		strcpy(next_word, current_word);
		strcat(next_word, last_word);
		
		free(last_word);
		last_word = current_word;
		current_word = next_word;
	}
	
	free(last_word);
	free(current_word);
	return 0;
}
Task: Text processing_1

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int badHrs, maxBadHrs;

static double hrsTot = 0.0;
static int rdgsTot = 0;
char bhEndDate[40];

int mungeLine( char *line, int lno, FILE *fout )
{
    char date[40], *tkn;
    int   dHrs, flag, hrs2, hrs;
    double hrsSum;
    int   hrsCnt = 0;
    double avg;

    tkn = strtok(line, ".");
    if (tkn) {
        int n = sscanf(tkn, "%s %d", &date, &hrs2);
        if (n<2) {
            printf("badly formated line - %d %s\n", lno, tkn);
            return 0;
        }
        hrsSum = 0.0;
        while( tkn= strtok(NULL, ".")) {
            n = sscanf(tkn,"%d %d %d", &dHrs, &flag, &hrs);
            if (n>=2) {
                if (flag > 0) {
                    hrsSum += 1.0*hrs2 + .001*dHrs;
                    hrsCnt += 1;
                    if (maxBadHrs < badHrs) {
                        maxBadHrs = badHrs;
                        strcpy(bhEndDate, date);
                    }
                    badHrs = 0;
                }
                else {
                    badHrs += 1;
                }
                hrs2 = hrs;
            }
            else {
                printf("bad file syntax line %d: %s\n",lno, tkn);
            }
        }
        avg = (hrsCnt > 0)? hrsSum/hrsCnt : 0.0;
        fprintf(fout, "%s  Reject: %2d  Accept: %2d  Average: %7.3f\n",
                date, 24-hrsCnt, hrsCnt, hrsSum/hrsCnt);
        hrsTot += hrsSum;
        rdgsTot += hrsCnt;
    }
    return 1;
}

int main()
{
    FILE *infile, *outfile;
    int lineNo = 0;
    char line[512];
    const char *ifilename = "readings.txt";
    outfile = fopen("V0.txt", "w");

    infile = fopen(ifilename, "rb");
    if (!infile) {
        printf("Can't open %s\n", ifilename);
        exit(1);
    }
    while (NULL != fgets(line, 512, infile)) {
        lineNo += 1;
        if (0 == mungeLine(line, lineNo, outfile))
            printf("Bad line at %d",lineNo);
    }
    fclose(infile);

    fprintf(outfile, "File:     %s\n", ifilename);
    fprintf(outfile, "Total:    %.3f\n", hrsTot);
    fprintf(outfile, "Readings: %d\n", rdgsTot);
    fprintf(outfile, "Average:  %.3f\n", hrsTot/rdgsTot);
    fprintf(outfile, "\nMaximum number of consecutive bad readings is %d\n", maxBadHrs);
    fprintf(outfile, "Ends on date %s\n", bhEndDate);
    fclose(outfile);
    return 0;
}
Task: Colour pinstripe_Display

C: #include<graphics.h>
#include<conio.h>

#define sections 4

int main()
{
	int d=DETECT,m,maxX,maxY,x,y,colour=0,increment=1;
	initgraph(&d,&m,"c:/turboc3/bgi");
	
	maxX = getmaxx();
	maxY = getmaxy();
	
	for(y=0;y<maxY;y+=maxY/sections)
	{
		for(x=0;x<maxX;x+=increment)
		{
			setfillstyle(SOLID_FILL,(colour++)%16);
			bar(x,y,x+increment,y+maxY/sections);
		}
		increment++;
		colour = 0;
	}
	
	getch();
	closegraph();
	return 0;
}
Task: Birthday problem

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define DEBUG 0 
#define DAYS 365
#define EXCESS (RAND_MAX / DAYS * DAYS)

int days[DAYS];

inline int rand_day(void)
{
	int n;
	while ((n = rand()) >= EXCESS);
	return n / (EXCESS / DAYS);
}


int simulate1(int p, int n)
{
	memset(days, 0, sizeof(days));

	while (p--)
		if (++days[rand_day()] == n) return 1;

	return 0;
}




double prob(int np, int n, double n_sigmas, double p_thresh, double *std_dev)
{
	double p, d; 
	int runs = 0, yes = 0;
	do {
		yes += simulate1(np, n);
		p = (double) yes / ++runs;
		d = sqrt(p * (1 - p) / runs);
		if (DEBUG > 1)
			printf("\t\t%d: %d %d %g %g        \r", np, yes, runs, p, d);
	} while (runs < 10 || fabs(p - p_thresh) < n_sigmas * d);
	if (DEBUG > 1) putchar('\n');

	*std_dev = d;
	return p;
}


int find_half_chance(int n, double *p, double *dev)
{
	int lo, hi, mid;

reset:
	lo = 0;
	hi = DAYS * (n - 1) + 1;
	do {
		mid = (hi + lo) / 2;

		
		
		
		*p = prob(mid, n, 5, .5, dev);

		if (DEBUG)
			printf("\t%d %d %d %g %g\n", lo, mid, hi, *p, *dev);

		if (*p < .5)	lo = mid + 1;
		else		hi = mid;

		if (hi < lo) {
			
			
			if (DEBUG) puts("\tMade a mess, will redo.");
			goto reset;
		}
	} while (lo < mid || *p < .5);

	return mid;
}

int main(void)
{
	int n, np;
	double p, d;
	srand(time(0));

	for (n = 2; n <= 5; n++) {
		np = find_half_chance(n, &p, &d);
		printf("%d collision: %d people, P = %g +/- %g\n",
			n, np, p, d);
	}

	return 0;
}
Task: Draw a sphere

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>

const char *shades = ".:!*oe&#%@";

double light[3] = { 30, 30, -50 };
void normalize(double * v)
{
        double len = sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
        v[0] /= len; v[1] /= len; v[2] /= len;
}

double dot(double *x, double *y)
{
        double d = x[0]*y[0] + x[1]*y[1] + x[2]*y[2];
        return d < 0 ? -d : 0;
}

void draw_sphere(double R, double k, double ambient)
{
        int i, j, intensity;
        double b;
        double vec[3], x, y;
        for (i = floor(-R); i <= ceil(R); i++) {
                x = i + .5;
                for (j = floor(-2 * R); j <= ceil(2 * R); j++) {
                        y = j / 2. + .5;
                        if (x * x + y * y <= R * R) {
                                vec[0] = x;
                                vec[1] = y;
                                vec[2] = sqrt(R * R - x * x - y * y);
                                normalize(vec);
                                b = pow(dot(light, vec), k) + ambient;
                                intensity = (1 - b) * (sizeof(shades) - 1);
                                if (intensity < 0) intensity = 0;
                                if (intensity >= sizeof(shades) - 1)
                                        intensity = sizeof(shades) - 2;
                                putchar(shades[intensity]);
                        } else
                                putchar(' ');
                }
                putchar('\n');
        }
}


int main()
{
        normalize(light);
        draw_sphere(20, 4, .1);
        draw_sphere(10, 2, .4);

        return 0;
}
Task: Thiele's interpolation formula

C: #include <stdio.h>
#include <string.h>
#include <math.h>

#define N 32
#define N2 (N * (N - 1) / 2)
#define STEP .05

double xval[N], t_sin[N], t_cos[N], t_tan[N];


double r_sin[N2], r_cos[N2], r_tan[N2];




double rho(double *x, double *y, double *r, int i, int n)
{
	if (n < 0) return 0;
	if (!n) return y[i];

	int idx = (N - 1 - n) * (N - n) / 2 + i;
	if (r[idx] != r[idx]) 
		r[idx] = (x[i] - x[i + n])
			/ (rho(x, y, r, i, n - 1) - rho(x, y, r, i + 1, n - 1))
			+ rho(x, y, r, i + 1, n - 2);
	return r[idx];
}

double thiele(double *x, double *y, double *r, double xin, int n)
{
	if (n > N - 1) return 1;
	return rho(x, y, r, 0, n) - rho(x, y, r, 0, n - 2)
		+ (xin - x[n]) / thiele(x, y, r, xin, n + 1);
}

#define i_sin(x) thiele(t_sin, xval, r_sin, x, 0)
#define i_cos(x) thiele(t_cos, xval, r_cos, x, 0)
#define i_tan(x) thiele(t_tan, xval, r_tan, x, 0)

int main()
{
	int i;
	for (i = 0; i < N; i++) {
		xval[i] = i * STEP;
		t_sin[i] = sin(xval[i]);
		t_cos[i] = cos(xval[i]);
		t_tan[i] = t_sin[i] / t_cos[i];
	}
	for (i = 0; i < N2; i++)
		
		r_sin[i] = r_cos[i] = r_tan[i] = 0/0.;

	printf("%16.14f\n", 6 * i_sin(.5));
	printf("%16.14f\n", 3 * i_cos(.5));
	printf("%16.14f\n", 4 * i_tan(1.));
	return 0;
}
Task: Longest string challenge

C: #include <stdio.h>
#include <string.h>
 
int cmp(const char *p, const char *q)
{
	while (*p && *q) p = &p[1], q = &q[1];
	return *p;
}
 
int main()
{
	char line[65536];
	char buf[1000000] = {0};
	char *last = buf;
	char *next = buf;
 
	while (gets(line)) {
		strcat(line, "\n");
		if (cmp(last, line)) continue;
		if (cmp(line, last)) next = buf;
		last = next;
		strcpy(next, line);
		while (*next) next = &next[1];
	}
 
	printf("%s", buf);
	return 0;
}
Task: Hello world_Line printer

C: #include <stdio.h>

int main()
{
   FILE *lp;
   lp = fopen("/dev/lp0","w");
   fprintf(lp,"Hello world!\n");
   fclose(lp);
   return 0;
}
Task: Magic squares of odd order

C: #include <stdio.h>
#include <stdlib.h>
 
int f(int n, int x, int y)
{
	return (x + y*2 + 1)%n;
}
 
int main(int argc, char **argv)
{
	int i, j, n;
 
	
	if(argc!=2) return 1;

	
	n = atoi(argv[1]);
	if (n < 3 || (n%2) == 0) return 2;
 
	for (i = 0; i < n; i++) {
		for (j = 0; j < n; j++)
			printf("% 4d", f(n, n - j - 1, i)*n + f(n, j, i) + 1);
		putchar('\n');
	}
	printf("\n Magic Constant: %d.\n", (n*n+1)/2*n);
 
	return 0;
}
Task: Extract file extension

C: #include <assert.h>
#include <ctype.h>
#include <string.h>
#include <stdio.h>


char* file_ext(const char *string)
{
    assert(string != NULL);
    char *ext = strrchr(string, '.');

    if (ext == NULL)
        return (char*) string + strlen(string);

    for (char *iter = ext + 1; *iter != '\0'; iter++) {
        if (!isalnum((unsigned char)*iter))
            return (char*) string + strlen(string);
    }

    return ext;
}

int main(void)
{
    const char *testcases[][2] = {
        {"http:
        {"CharacterModel.3DS", ".3DS"},
        {".desktop", ".desktop"},
        {"document", ""},
        {"document.txt_backup", ""},
        {"/etc/pam.d/login", ""}
    };

    int exitcode = 0;
    for (size_t i = 0; i < sizeof(testcases) / sizeof(testcases[0]); i++) {
        const char *ext = file_ext(testcases[i][0]);
        if (strcmp(ext, testcases[i][1]) != 0) {
            fprintf(stderr, "expected '%s' for '%s', got '%s'\n",
                testcases[i][1], testcases[i][0], ext);
            exitcode = 1;
        }
    }
    return exitcode;
}
Task: Permutation test

C: #include <stdio.h>

int data[] = {  85, 88, 75, 66, 25, 29, 83, 39, 97,
                68, 41, 10, 49, 16, 65, 32, 92, 28, 98 };

int pick(int at, int remain, int accu, int treat)
{
        if (!remain) return (accu > treat) ? 1 : 0;

        return  pick(at - 1, remain - 1, accu + data[at - 1], treat) +
                ( at > remain ? pick(at - 1, remain, accu, treat) : 0 );
}

int main()
{
        int treat = 0, i;
        int le, gt;
        double total = 1;
        for (i = 0; i < 9; i++) treat += data[i];
        for (i = 19; i > 10; i--) total *= i;
        for (i = 9; i > 0; i--) total /= i;

        gt = pick(19, 9, 0, treat);
        le = total - gt;

        printf("<= : %f%%  %d\n > : %f%%  %d\n",
               100 * le / total, le, 100 * gt / total, gt);
        return 0;
}
Task: Compiler_lexical analyzer

C: if ( p  ) {
    print ( n , " " ) ;
    count = count + 1 ; 
}
Task: Keyboard input_Obtain a Y or N response

C: #include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
 
void set_mode(int want_key)
{
	static struct termios old, new;
	if (!want_key) {
		tcsetattr(STDIN_FILENO, TCSANOW, &old);
		return;
	}
 
	tcgetattr(STDIN_FILENO, &old);
	new = old;
	new.c_lflag &= ~(ICANON);
	tcsetattr(STDIN_FILENO, TCSANOW, &new);
}
 
int get_key(int no_timeout)
{
	int c = 0;
	struct timeval tv;
	fd_set fs;
	tv.tv_usec = tv.tv_sec = 0;
 
	FD_ZERO(&fs);
	FD_SET(STDIN_FILENO, &fs);

	select(STDIN_FILENO + 1, &fs, 0, 0, no_timeout ? 0 : &tv);
	if (FD_ISSET(STDIN_FILENO, &fs)) {
		c = getchar();
		set_mode(0);
	}
	return c;
}
 
int main()
{
	int c;
	while(1) {
		set_mode(1);
		while (get_key(0)); 
		printf("Prompt again [Y/N]? ");
		fflush(stdout);

		c = get_key(1);
		if (c == 'Y' || c == 'y') {
			printf("\n");
			continue;
		}

		if (c == 'N' || c == 'n') {
			printf("\nDone\n");
			break;
		}

		printf("\nYes or no?\n");
	}

	return 0;
}
Task: Entropy_Narcissist

C: #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <math.h>

#define MAXLEN 961 

int makehist(char *S,int *hist,int len){
	int wherechar[256];
	int i,histlen;
	histlen=0;
	for(i=0;i<256;i++)wherechar[i]=-1;
	for(i=0;i<len;i++){
		if(wherechar[(int)S[i]]==-1){
			wherechar[(int)S[i]]=histlen;
			histlen++;
		}
		hist[wherechar[(int)S[i]]]++;
	}
	return histlen;
}

double entropy(int *hist,int histlen,int len){
	int i;
	double H;
	H=0;
	for(i=0;i<histlen;i++){
		H-=(double)hist[i]/len*log2((double)hist[i]/len);
	}
	return H;
}

int main(void){
	char S[MAXLEN];
	int len,*hist,histlen;
	double H;
	FILE *f;
	f=fopen("entropy.c","r");
	for(len=0;!feof(f);len++)S[len]=fgetc(f);
	S[--len]='\0';
	hist=(int*)calloc(len,sizeof(int));
	histlen=makehist(S,hist,len);
	
	H=entropy(hist,histlen,len);
	printf("%lf\n",H);
	return 0;
}