Task: Password generator
C: #include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define DEFAULT_LENGTH 4
#define DEFAULT_COUNT 1

char* symbols[] = {"ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz", "0123456789", "!\"#$%&'()*+,-./:;<=>?@[]^_{|}~"};
int length = DEFAULT_LENGTH;
int count = DEFAULT_COUNT;
unsigned seed;
char exSymbols = 0;

void GetPassword () {
    
    int lengths[4] = {1, 1, 1, 1};
    int count = 4;
    while (count < length) {
        lengths[rand()%4]++;
        count++;
    } 

    
    char password[length + 1];
    for (int i = 0; i < length; ) { 
        
        int str = rand()%4;
        if (!lengths[str])continue;   

        char c;
        switch (str) {
            case 2:
                c = symbols[str][rand()%10];
                while (exSymbols && (c == 'I' || c == 'l' || c == '1' || c == 'O' || c == '0' || c == '5' || c == 'S' || c == '2' || c == 'Z'))
                    c = symbols[str][rand()%10];
                password[i] = c;
            break;

            case 3:
                c = symbols[str][rand()%30];
                while (exSymbols && (c == 'I' || c == 'l' || c == '1' || c == 'O' || c == '0' || c == '5' || c == 'S' || c == '2' || c == 'Z'))
                    c = symbols[str][rand()%30];
                password[i] = c;
            break;

            default:
                c = symbols[str][rand()%26];
                while (exSymbols && (c == 'I' || c == 'l' || c == '1' || c == 'O' || c == '0' || c == '5' || c == 'S' || c == '2' || c == 'Z'))  
                    c = symbols[str][rand()%26];
                password[i] = c;
            break;
        }

        i++;
        lengths[str]--;
    }

    password [length] = '\0';
    printf ("%s\n", password);
}

int main (int argc, char* argv[]) {
    seed = (unsigned)time(NULL);

    
    for (int i = 1; i < argc; i++) {
        switch (argv[i][1]) {
            case 'l':
                if (sscanf (argv[i+1], "%d", &length) != 1) {
                    puts ("Unrecognized input. Syntax: -l [integer]");
                    return -1;
                }
                
                if (length < 4) {
                    puts ("Password length must be at least 4 characters.");
                    return -1;
                }
                i++;                
            break;

            case 'c':
                if (sscanf (argv[i+1], "%d", &count) != 1) {
                    puts ("Unrecognized input. Syntax: -c [integer]");
                    return -1;
                }

                if (count <= 0) {
                    puts ("Count must be at least 1.");
                    return -1;
                }
                i++;
            break;

            case 's':
                if (sscanf (argv[i+1], "%d", &seed) != 1) {
                    puts ("Unrecognized input. Syntax: -s [integer]");
                    return -1;
                }
                i++;
            break;

            case 'e':
                exSymbols = 1;
            break;

            default:
                help:
                printf ("Help:\nThis program generates a random password.\n"
                "Commands:"
                   "Set password length: -l [integer]\n"
                   "Set password count: -c [integer]\n"
                   "Set seed: -s [integer]\n"
                   "Exclude similiar characters: -e\n"
                   "Display help: -h");
                return 0;
            break;
        }    
    }

    srand (seed);

    for (int i = 0; i < count; i++)
        GetPassword();
    
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <ctime>

const std::string CHR[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz", 
                            "0123456789", "!\"#$%&'()*+,-./:;<=>?@[]^_{|}~" };
const std::string UNS = "O0l1I5S2Z";

std::string createPW( int len, bool safe ) {
    std::string pw;
    char t;
    for( int x = 0; x < len; x += 4 ) {
        for( int y = x; y < x + 4 && y < len; y++ ) {
            do {
                t = CHR[y % 4].at( rand() % CHR[y % 4].size() );
            } while( safe && UNS.find( t ) != UNS.npos );
            pw.append( 1, t );
        }
    }
    std::random_shuffle( pw.begin(), pw.end() );
    return pw;
}
void generate( int len, int count, bool safe ) {
    for( int c = 0; c < count; c++ ) {
        std::cout << createPW( len, safe ) << "\n";
    }
    std::cout << "\n\n";
}
int main( int argc, char* argv[] ){
    if( argv[1][1] == '?' || argc < 5 ) {
        std::cout << "Syntax: PWGEN length count safe seed /?\n"
                     "length:\tthe length of the password(min 4)\n"
                     "count:\thow many passwords should be generated\n"
                     "safe:\t1 will exclude visually similar characters, 0 won't\n"
                     "seed:\tnumber to seed the random generator or 0\n"
                     "/?\tthis text\n\n";
    } else {
        int l = atoi( argv[1] ),
            c = atoi( argv[2] ),
            e = atoi( argv[3] ), 
            s = atoi( argv[4] );
        if( l < 4 ) {
            std::cout << "Passwords must be at least 4 characters long.\n\n";
        } else {
            if (s == 0) {
               std::srand( time( NULL ) );
            } else {
               std::srand( unsigned( s ) );
            }
            generate( l, c, e != 0 );
        }
    }
    return 0;   
}