C語言標準函式庫
#include <string.h>
char * strcpy(char * destination, const char * source);
char * strncpy(char *dest, const char *src, size_t count);
void * memcpy(void *dest, const void *src, size_t length);
void * memset(void *dest, int value, size_t num);
int strcmp(const char *str1, const char *str2); // return 0 if str1 == str2 else 1
int strlen(const char *str1); // not include '\0'
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