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//得10分，基本上所有的情况，都考虑到了 //如果有考虑到源目所指区域有重叠的情况，加1分！ char * strcpy( char *strDest, const char *strSrc ) { if(strDest == strSrc) { return strDest; } assert( (strDest != NULL) && (strSrc != NULL) ); char *address = strDest; while( (*strDest++ = * strSrc++) != '\0' ); return address; } //@yansha:字串末尾要加结束符'\0'，不然输出错位结果 char *strncpy(char *strDes, const char *strSrc, unsigned int count) { assert(strDes != NULL && strSrc != NULL); char *address = strDes; while (count-- && *strSrc != '\0') *strDes++ = *strSrc++; *strDes = '\0'; return address; } //查找字符串s中首次出现字符c的位置 char *strchr(const char *str, int c) { assert(str != NULL); for (; *str != (char)c; ++ str) if (*str == '\0') return NULL; return str; } int strcmp(const char *s, const char *t) { assert(s != NULL && t != NULL); while (*s && *t && *s == *t) { ++ s; ++ t; } return (*s - *t); } char *strcat(char *strDes, const char *strSrc) { assert((strDes != NULL) && (strSrc != NULL)); char *address = strDes; while (*strDes != '\0') ++ strDes; while ((*strDes ++ = *strSrc ++) != '\0') NULL; return address; } int strlen(const char *str) { assert(str != NULL); int len = 0; while (*str ++ != '\0') ++ len; return len; } //此函数，梦修改如下 char *strdup_(char *strSrc) //将字符串拷贝到新的位置 { if(strSrc!=NULL) { char *start=strSrc; int len=0; while(*strSrc++!='\0') len++; char *address=(char *)malloc(len+1); assert(address != NULL); while((*address++=*start++)!='\0'); return address-(len+1); } return NULL; } //多谢laoyi19861011指正 char *strstr(const char *strSrc, const char *str) { assert(strSrc != NULL && str != NULL); const char *s = strSrc; const char *t = str; for (; *strSrc != '\0'; ++ strSrc) { for (s = strSrc, t = str; *t != '\0' && *s == *t; ++s, ++t) NULL; if (*t == '\0') return (char *) strSrc; } return NULL; } char *strncat(char *strDes, const char *strSrc, unsigned int count) { assert((strDes != NULL) && (strSrc != NULL)); char *address = strDes; while (*strDes != '\0') ++ strDes; while (count -- && *strSrc != '\0' ) *strDes ++ = *strSrc ++; *strDes = '\0'; return address; } int strncmp(const char *s, const char *t, unsigned int count) { assert((s != NULL) && (t != NULL)); while (*s && *t && *s == *t && count --) { ++ s; ++ t; } return (*s - *t); } char *strpbrk(const char *strSrc, const char *str) { assert((strSrc != NULL) && (str != NULL)); const char *s; while (*strSrc != '\0') { s = str; while (*s != '\0') { if (*strSrc == *s) return (char *) strSrc; ++ s; } ++ strSrc; } return NULL; } int strcspn(const char *strSrc, const char *str) { assert((strSrc != NULL) && (str != NULL)); const char *s; const char *t = strSrc; while (*t != '\0') { s = str; while (*s != '\0') { if (*t == *s) return t - strSrc; ++ s; } ++ t; } return 0; } int strspn(const char *strSrc, const char *str) { assert((strSrc != NULL) && (str != NULL)); const char *s; const char *t = strSrc; while (*t != '\0') { s = str; while (*s != '\0') { if (*t == *s) break; ++ s; } if (*s == '\0') return t - strSrc; ++ t; } return 0; } char *strrchr(const char *str, int c) { assert(str != NULL); const char *s = str; while (*s != '\0') ++ s; for (-- s; *s != (char) c; -- s) if (s == str) return NULL; return (char *) s; } char* strrev(char *str) { assert(str != NULL); char *s = str, *t = str, c; while (*t != '\0') ++ t; for (-- t; s < t; ++ s, -- t) { c = *s; *s = *t; *t = c; } return str; } char *strnset(char *str, int c, unsigned int count) { assert(str != NULL); char *s = str; for (; *s != '\0' && s - str < count; ++ s) *s = (char) c; return str; } char *strset(char *str, int c) { assert(str != NULL); char *s = str; for (; *s != '\0'; ++ s) *s = (char) c; return str; } //@heyaming //对原 strtok 的修改，根据MSDN,strToken可以为NULL.实际上第一次call strtok给定一字串， //再call strtok时可以输入NULL代表要接着处理给定字串。 //所以需要用一 static 保存没有处理完的字串。同时也需要处理多个分隔符在一起的情况。 char *strtok(char *strToken, const char *str) { assert(str != NULL); static char *last; if (strToken == NULL && (strToken = last) == NULL) return (NULL); char *s = strToken; const char *t = str; while (*s != '\0') { t = str; while (*t != '\0') { if (*s == *t) { last = s + 1; if (s - strToken == 0) { strToken = last; break; } *(strToken + (s - strToken)) = '\0'; return strToken; } ++ t; } ++ s; } return NULL; } char *strupr(char *str) { assert(str != NULL); char *s = str; while (*s != '\0') { if (*s >= 'a' && *s <= 'z') *s -= 0x20; s ++; } return str; } char *strlwr(char *str) { assert(str != NULL); char *s = str; while (*s != '\0') { if (*s >= 'A' && *s <= 'Z') *s += 0x20; s ++; } return str; } void *memcpy(void *dest, const void *src, unsigned int count) { assert((dest != NULL) && (src != NULL)); void *address = dest; while (count --) { *(char *) dest = *(char *) src; dest = (char *) dest + 1; src = (char *) src + 1; } return address; } void *memccpy(void *dest, const void *src, int c, unsigned int count) { assert((dest != NULL) && (src != NULL)); while (count --) { *(char *) dest = *(char *) src; if (* (char *) src == (char) c) return ((char *)dest + 1); dest = (char *) dest + 1; src = (char *) src + 1; } return NULL; } void *memchr(const void *buf, int c, unsigned int count) { assert(buf != NULL); while (count --) { if (*(char *) buf == c) return (void *) buf; buf = (char *) buf + 1; } return NULL; } int memcmp(const void *s, const void *t, unsigned int count) { assert((s != NULL) && (t != NULL)); while (*(char *) s && *(char *) t && *(char *) s == *(char *) t && count --) { s = (char *) s + 1; t = (char *) t + 1; } return (*(char *) s - *(char *) t); } //@big： //要处理src和dest有重叠的情况，不是从尾巴开始移动就没问题了。 //一种情况是dest小于src有重叠，这个时候要从头开始移动， //另一种是dest大于src有重叠，这个时候要从尾开始移动。 void *memmove(void *dest, const void *src, unsigned int count) { assert(dest != NULL && src != NULL); char* pdest = (char*) dest; char* psrc = (char*) src; //pdest在psrc后面，且两者距离小于count时，从尾部开始移动. 其他情况从头部开始移动 if (pdest > psrc && pdest - psrc < count) { while (count--) { *(pdest + count) = *(psrc + count); } } else { while (count--) { *pdest++ = *psrc++; } } return dest; } void *memset(void *str, int c, unsigned int count) { assert(str != NULL); void *s = str; while (count --) { *(char *) s = (char) c; s = (char *) s + 1; } return str; } 转载地址：http://dbvvi.baihongyu.com/