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  • 关于printf系列函数

    #include <stdio.h>

    int printf(const char *format, ...);
    int fprintf(FILE *
    stream, const char *format, ...);
    int sprintf(char *
    str, const char *format, ...);
    int snprintf(char *
    str, size_t size, const char *format, ...);

    #include <stdarg.h>

    int vprintf(const char *format, va_list ap);
    int vfprintf(FILE *
    stream, const char *format, va_list ap);
    int vsprintf(char *
    str, const char *format, va_list ap);
    int vsnprintf(char *
    str, size_t size, const char *format, va_list ap);

      

    he functions in the printf() family produce output according to a format as described below. The functions printf() and vprintf() write output to stdout, the standard output stream; fprintf() and vfprintf() write output to the given output streamsprintf(), snprintf(),vsprintf() and vsnprintf() write to the character string str.

    The functions vprintf(), vfprintf(), vsprintf(), vsnprintf() are
    equivalent to the functions printf(), fprintf(), sprintf(), snprintf(), respectively, except that they are called with a va_list instead of a variable number of arguments. These functions do not call the va_end macro. Consequently, the value of ap is undefined after the call. The application should call va_end(ap) itself afterwards. 

     

    In ISO C99, snprintf was introduced as an alternative to sprintf that can help avoid the risk of a buffer overflow: 

    int snprintf(char *str, size_t size, const char * restrict format, ...)

    snprintf is guaranteed not to write more than size bytes into str, so use of it can help avoid the risk of a buffer overflow, as in the following code fragment: 

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  • 原文地址:https://www.cnblogs.com/welkinwalker/p/1977554.html
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