user-0 提问: poj1299

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user: user-0
content: 我改成了scanf就不存在这样的问题了，但是输出结果有问题，测试数据为100 50 90的时候，我的输出为YES 18，但是，正解为NO 250? 为什么？  #include<stdio.h> #include<stdlib.h> #include<string.h> #define PI 3.14159 int main() {     int x,y,z;     char reciv[11];     while(1)     {         double dist,gallo_need;         scanf("%s",reciv);         if(strcmp(reciv,"ENDOFINPUT")==0)             break;         scanf("%d %d %d",&x,&y,&z);         scanf("%s",reciv)         if(z>180)         {             z=360-z;         }         dist=2*PI*x*z/360;         gallo_need=dist/5;         if(gallo_need>y)         {             printf("NO %d\n",y*5);         }         else             printf("YES %d\n",(int)(y-gallo_need));     }     return 0; }

user: user-0
content: 能解释下吗？

user: user-1
content: gets(reciv); if (0==reciv[0]) continue;

user: user-1
content: gets, _getws Get a line from the stdin stream.  char *gets( char *buffer );  wchar_t *_getws( wchar_t *buffer );  Routine Required Header Compatibility  gets <stdio.h> ANSI, Win 95, Win NT  _getws <stdio.h> or <wchar.h> ANSI, Win 95, Win NT    For additional compatibility information, see Compatibility in the Introduction.  Libraries  LIBC.LIB Single thread static library, retail version  LIBCMT.LIB Multithread static library, retail version  MSVCRT.LIB Import library for MSVCRT.DLL, retail version    Return Value  Each of these functions returns its argument if successful. A NULL pointer indicates an error or end-of-file condition. Use ferror or feof to determine which one has occurred.  Parameter  buffer  Storage location for input string  Remarks  The gets function reads a line from the standard input stream stdin and stores it in buffer. The line consists of all characters up to and including the first newline character ('\n'). gets then replaces the newline character with a null character ('\0') before returning the line. In contrast, the fgets function retains the newline character. _getws is a wide-character version of gets; its argument and return value are wide-character strings.  Generic-Text Routine Mappings  TCHAR.H Routine  _UNICODE & _MBCS Not Defined _MBCS Defined _UNICODE Defined  _getts gets gets _getws    Example  /* GETS.C */  #include <stdio.h>  void main( void ) {    char line[81];     printf( "Input a string: " );    gets( line );    printf( "The line entered was: %s\n", line ); }   Output  Input a string: Hello! The line entered was: Hello!   Stream I/O Routines  See Also   fgets, fputs, puts

user: user-1
content: Format Specification Fields: scanf and wscanf Functions A format specification has the following form:  % [width] [{h | l | I64 | L}]type  The format argument specifies the interpretation of the input and can contain one or more of the following:   White-space characters: blank (' '); tab ('\t'); or newline ('\n'). A white-space character causes scanf to read, but not store, all consecutive white-space characters in the input up to the next non–white-space character. One white-space character in the format matches any number (including 0) and combination of white-space characters in the input.   Non–white-space characters, except for the percent sign (%). A non–white-space character causes scanf to read, but not store, a matching non–white-space character. If the next character in stdin does not match, scanf terminates.   Format specifications, introduced by the percent sign (%). A format specification causes scanf to read and convert characters in the input into values of a specified type. The value is assigned to an argument in the argument list.  The format is read from left to right. Characters outside format specifications are expected to match the sequence of characters in stdin; the matching characters in stdin are scanned but not stored. If a character in stdin conflicts with the format specification, scanf terminates, and the character is left in stdin as if it had not been read.  When the first format specification is encountered, the value of the first input field is converted according to this specification and stored in the location that is specified by the first argument. The second format specification causes the second input field to be converted and stored in the second argument, and so on through the end of the format string.  An input field is defined as all characters up to the first white-space character (space, tab, or newline), or up to the first character that cannot be converted according to the format specification, or until the field width (if specified) is reached. If there are too many arguments for the given specifications, the extra arguments are evaluated but ignored. The results are unpredictable if there are not enough arguments for the format specification.  Each field of the format specification is a single character or a number signifying a particular format option. The type character, which appears after the last optional format field, determines whether the input field is interpreted as a character, a string, or a number.   The simplest format specification contains only the percent sign and a type character (for example, %s). If a percent sign (%) is followed by a character that has no meaning as a format-control character, that character and the following characters (up to the next percent sign) are treated as an ordinary sequence of characters, that is, a sequence of characters that must match the input. For example, to specify that a percent-sign character is to be input, use %%.  An asterisk (*) following the percent sign suppresses assignment of the next input field, which is interpreted as a field of the specified type. The field is scanned but not stored.

user: user-0
content: 代码AC了，不过是用的scanf，为什么scanf就不存在缓冲区的问题，scanf为什么不会把缓冲区的\n赋给reciv呢？

user: user-0
content: 我把代码改成这样，虽然能正确输出，可是提交上去，提示ouput limint exceed，我这个程序是有break的，怎么会是死循环呢？ 还有那个fflush是什么意思呢？我知道他是清除缓冲区的，但是其中的原理不是太懂？ #include<stdio.h> #include<stdlib.h> #include<string.h> #define PI 3.14159 int main() {     int x,y,z;     char reciv[11];     while(1)     {         fflush(stdin);         int dist,gallo_need;         gets(reciv);         if(strcmp(reciv,"END")==0)             continue;         if(strcmp(reciv,"ENDOFINPUT")==0)             break;         scanf("%d %d %d",&x,&y,&z);         dist=2*PI*x*z/360;         gallo_need=dist/5;         if(gallo_need>y)         {             printf("NO %d\n",y*5);         }         else             printf("YES %d\n",y-gallo_need);     }     return 0; }

user: user-0
content: 大哥，为什么呢？能解释下细节吗？

user: user-2
content: 在gets()后加上fflush(stdin);  gets(reciv); fflush(stdin);