strcmp的原型翻译string compare，作用：字符串比较，而且仅限于字符串大小的比较；原型：int strcmp(const char *s1, const char *s2);
返回值：
s1 = s2 ret = 0
s1 > s2 ret = 1
s1 < s2 ret = -1
实例：
vps云服务器 #include <stdio.h>int main(void){ char arr1[10] = “ABCDEF”; char arr2[10] = “ABCDEF”; char arr3[10] = “6666”; char arr4[10] = “5555”; char arr5[10] = “111”; char arr6[10] = “222”; printf(“vl1 = %d.\n”, strcmp(arr1, arr2)); printf(“vl2 = %d.\n”, strcmp(arr3, arr4)); printf(“vl3 = %d.\n”, strcmp(arr5, arr6)); return 0;}
输出结果：
// vl1 = 0.
// vl2 = 1.
// vl3 = -1.
strncmp是用来比较两个字符串前n个字节大小，区分大小写。原型：int strncmp(const char *s1, const char *s2, size_t n);
返回值和strcmp一样；
返回值：
?????????????? s1 = s2????????? ret = 0
?????????????? s1 > s2????????? ret = 1
?????????????? s1 < s2????????? ret = -1
