The implementation of string Operation function in C language

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# include # include # include / * string library function collection * / int my_strlen (const char * str) {int ret = 0; assert (str! = NULL); while (* str++! ='\ 0') + ret; return ret;} / * must not customize the variable * / int my_strlen2 (const char * str) {if ((* str) = ='\ 0') return 0 Else return (1 + my_strlen (+ + str));} / / = string lookup = / / char * my_strstr (char * strSrc, char * substr) {int I, j; int lenstr, sublen; int num; if (strSrc = = NULL | | substr = = NULL) return NULL; lenstr = strlen (strSrc); sublen = strlen (substr); if (lenstr < sublen) return NULL; num = lenstr-sublen; for (I = 0; I