C库中的snprintf（）-yiteyi-C++库

函数的作用是：在数组缓冲区中格式化并存储一系列字符和值。snprintf（）函数，其中添加了n参数，该参数指示要写入缓冲区的最大字符数（包括null字符末尾的字符数）。定义见头文件。

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snprintf（）函数用于将printf（）函数的输出重定向到缓冲区。

snprintf（）还返回写入缓冲区的字符数（不包括空终止符），类似于printf语句，它返回在stdout中打印的字符数。

语法：

int snprintf(char *str, size_t size, const char *format, ...);*str : is a buffer.size : is the maximum number of bytes(characters) that will be written to the buffer.format : C string that contains a formatstring that follows the same specifications as format in printf... : the optional ( …) arguments are just the string formats like (“%d”, myint) as seen in printf.

C

                         // C program to demonstrate snprintf()                       
                         #include <stdio.h>                       
           
                         int                                     main()                       
                         {                       
                                                 char                                     buffer[50];                       
                                                 char                                     * s =                                     "geeksforgeeks"                                     ;                       
           
                                                 // Counting the character and storing                       
                                                 // in buffer using snprintf                       
                                                 int                                     j = snprintf(buffer, 6,                                     "%s"                                     , s);                       
           
                                                 // Print the string stored in buffer and                       
                                                 // character count                       
                                                 printf                                     (                                     "string:%scharacter count = %d"                                     ,                       
                                                 buffer, j);                       
                                   
                                                 // join two or more strings                       
                                                 char                                     *str1 =                                     "quick"                                     ;                       
                                                 char                                     *str2 =                                     "brown"                                     ;                       
                                                 char                                     *str3 =                                     "lazy"                                     ;                       
                                                 int                                     max_len =                                     sizeof                                     buffer;                       
                                   
                                                 j = snprintf (buffer, max_len,                                     "The %s %s fox jumped over the %s dog."                                     , str1, str2, str3);                       
                                                 printf                                     (                                     "The number of bytes printed to 'buffer' (excluding the null terminator) is %d"                                     , j);                       
                                                 if                                     (j >= max_len)                       
                                                 fputs                                     (                                     "Buffer length exceeded; string truncated"                                     , stderr);                       
                                                 puts                                     (                                     "Joined string:"                                     );                       
                                                 puts                                     (buffer);                       
           
                                                 return                                     0;                       
                         }                       

输出

string:geekscharacter count = 14The number of bytes printed to 'buffer' (including the null terminator) is 45Joined string:The quick brown fox jumped over the lazy dog.

输出：

string:geekscharacter count = 14

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