//例子多点自然就懂了。int snprintf(char *restrict buf, size_t n, const char * restrict format, ...);函数说明:最多从源串中拷贝n－1个字符到目标串中，然后再在后面加一个0。所以如果目标串的大小为n 的话，将不会溢出。函数返回值:若成功则返回欲写入的字符串长度，若出错则返回负值。Result1(推荐的用法)#include #include int main(){ char str[10]={0,}; snprintf(str, sizeof(str), "0123456789012345678"); printf("str=%s\n", str); return 0;}root] /root/lindatest$ ./teststr=012345678Result2:(不推荐使用)#include #include int main(){ char str[10]={0, }; snprintf(str, 18, "0123456789012345678"); printf("str=%s\n", str); return 0;}root] /root/lindatest$ ./teststr=01234567890123456snprintf函数返回值的测试：#include #include int main(){ char str1[10] ={0, }; char str2[10] ={0, }; int ret1=0,ret2=0; ret1=snprintf(str1, sizeof(str1), "%s", "abc"); ret2=snprintf(str2, 4, "%s", "aaabbbccc"); printf("aaabbbccc length=%d\n", strlen("aaabbbccc")); printf("str1=%s,ret1=%d\n", str1, ret1); printf("str2=%s,ret2=%d\n", str2, ret2); return 0;}[root] /root/lindatest$ ./testaaabbbccc length=9str1=abc,ret1=3str2=aaa,ret2=9
snprintf int snprintf(char *str, size_t size, const char *format, ...); 将可变个参数(...)按照format格式化成字符串，然后将其复制到str中 (1) 如果格式化后的字符串长度 < size，则将此字符串全部复制到str中，并给其后添加一个字符串结束符('\0')； (2) 如果格式化后的字符串长度 >= size，则只将其中的(size-1)个字符复制到str中，并给其后添加一个字符串结束符('\0') 函数返回值:若成功则返回欲写入的字符串长度，若出错则返回负值。 -------------------------------------------- #include //snprintf() #include //strlen() int main() { char name[30]; char *name = "yangtaiping"; printf("strlen(name) = %d\n", strlen(name)); snprintf(name, strlen(name), "姓名：%s", name); printf("name = %s\n", name); printf("strlen(name) = %d\n", strlen(name)); } strcpy() sprintf() strcat() 存在安全隐患， 其对应的安全版为：strncpy() snprintf() strncat() 。 snprintf(s, 100, "%.*S", 3, "abcd");s的值为abc %.*s 表示有两项， 第一项指定了长度，第二项则是%s的内容，所以取前三位 词条图册更多图册 Let len be the length of the formatted data string (not including the terminating null). len and count are in bytes for _snprintf, wide characters for _snwprintf. If len < count, then len characters are stored in buffer, a null-terminator is appended, and len is returned. If len = count, then len characters are stored in buffer, no null-terminator is appended, and len is returned. If len > count, then count characters are stored in buffer, no null-terminator is appended, and a negative value is returned. "如果字符串很长，超过了buffer的size，是否会截断后还是在buffer末尾添'\0'？" If len > count, then count characters are stored in buffer, no null-terminator is appended, and a negative value is returned. 回答完毕。 以上是vc里ok，linux下的snprintf截断后会添加'\0'，这个要注意。