string.h 的实现

      最近很是烦躁，没做什么事，随便花了点时间把 C 库中的 string.h 中的几个函数实现了下，不多说了，直接贴代码吧，可能会存在错误和不好的算法，希望大家见谅：

       测试函数写的乱七八糟，就不贴在这里了，有些函数是不需要实现差错控制的，使用不当，程序崩溃那是自己的事，我实现的这些个函数可能和经典的实现存在较大的差距，不过，我说过了，这仅仅是个人觉得好玩才随便写的，我也没那么多的时间去一一验证和调试。

dlut_string.h

/* * dlut_string.h * *  Created on: 2013年12月18日 *      Author: DLUTBruceZhang */#ifndef DLUT_STRING_H_#define DLUT_STRING_H_#include <malloc.h>#include <stdio.h>#define dlut_strcmpi(buf1, buf2)dlut_stricmp(buf1, buf2)void * dlut_memcpy(void *, const void *, unsigned int);intdlut_memcmp(const void *, const void *, unsigned int);void *dlut_memset(void *, int, unsigned int);char *dlut_strset(char *, int);char *dlut_strcpy(char *, const char *);char *dlut_strcat(char *, const char *);intdlut_strcmp(const char *, const char *);unsigned int dlut_strlen(const char *);void *dlut_memccpy(void *, const void *, int, unsigned int);void *dlut_memchr(void *, int, unsigned int);intdlut_memicmp(const void *, const void *, unsigned int);void *dlut_memmove(void *, const void *, unsigned int);char *dlut_strchr(const char *, int);intdlut_stricmp(const char *, const char *);intdlut_strcoll(const char *, const char *);int dlut_stricoll(const char *, const char *);intdlut_strncoll(const char *, const char *, unsigned int);intdlut_strnicoll(const char *, const char *, unsigned int);unsigned intdlut_strcspn(const char *, const char *);char *dlut_strdup(const char *);char *dlut_strerror(const char *);char *dlut_strlwr(char *);char *dlut_strncat(char *, const char *, unsigned int);intdlut_strncmp(const char *, const char *, unsigned int);intdlut_strnicmp(const char *, const char *, unsigned int);char *dlut_strncpy(char *, const char *, unsigned int);char *dlut_strnset(char *, int , unsigned int);char *dlut_strpbrk(const char *, const char *);char *dlut_strrchr(const char *, int);char *dlut_strrev(char *);unsigned int dlut_strspn(const char *, const char *);char *dlut_strstr(const char *, const char *);char *dlut_strtok(char *, const char *);char *dlut_strupr(char *);intdlut_bcmp(const void *, const void *, unsigned int);voiddlut_bcopy(const void *, void *, unsigned int);voiddlut_bzero(void *, unsigned int);#endif /* DLUT_STRING_H_ */

dlut_string.c

/* * dlut_string.c * *  Created on: 2013年12月18日 *      Author: DLUTBruceZhang */#include "dlut_string.h"void * dlut_memcpy(void *dst, const void *src, unsigned int size){void *dst_ = dst;if (src == 0 || dst == 0 || !size)return dst_;while (size-- && *(char *)src){*(char *)dst++ = *(char *)src++;}return dst_;}int dlut_memcmp(const void *buf1, const void *buf2, unsigned int size){char *buf1_ = (char *)buf1;char *buf2_ = (char *)buf2;if (!size)return 0;while (size-- && *buf1_ == *buf2_){buf1_++;buf2_++;}return *buf1_ - *buf2_;}void * dlut_memset(void *buf, int v, unsigned int size){void *buf_ = buf;if (!size)return buf_;while (size--){*(char *)buf = (char)v;buf = (char *)buf + 1;}return buf_;}char * dlut_strset(char *buf, int v){char *start = buf;while (*buf){*buf++ = (char)v;}return start;}char * dlut_strcpy(char *dst, const char *src){char *start = dst;while (*src){*dst++ = *src++;}return start;}char * dlut_strcat(char *buf, const char *sub){char *start = buf;while (*buf)buf++;while (*sub){*buf++ = *sub++;}return start;}int dlut_strcmp(const char *buf1, const char *buf2){while (*buf1 == *buf2){buf1++;buf2++;}return *buf1 - *buf2;}unsigned int dlut_strlen(const char *buf){int i = 0;while (*buf){buf++;i++;}return i;}void * dlut_memccpy(void *dst, const void *src, int v, unsigned int size){while (size-- && (int)*(char *)src != v){*(char *)dst++ = *(char *)src++;}if (*(char *)src == v)return (void *)++src;elsereturn 0;}void * dlut_memchr(void *str, int v, unsigned int size){while (size-- && (int)*(char *)str != v)str++;return (int)*(char *)str == v ? str : 0;}#define DLUT_TO_LOWER(c)(c >= 'A' && c <= 'Z') ? (c + 'a' - 'A') : cint dlut_memicmp(const void *buf1, const void *buf2, unsigned int size){char buf1_;char buf2_;while (size-- &&((buf1_ = DLUT_TO_LOWER(*(char *)buf1)) == (buf2_ = DLUT_TO_LOWER(*(char *)buf2)))){buf1 = (char *)buf1 + 1;buf2 = (char *)buf2 + 1;}return (int)*(char *)buf1 - (int)*(char *)buf2;}/* * this function is similar to dlut_memcpy, but you need know, * dlut_memmove support memory overlapping, its method is here: * 1.if src address is equal dst address, dont't do any thing * 2.if src address is less than dst address, do reverse copy * 3.if src address is greater than dst address, do forward copy * * */void * dlut_memmove(void *dst, const void *src, unsigned int size){void *dst_ = dst;if (src > dst){while (size--){*(char *)dst++ = *(char *)src++;}}else if (src < dst){src = (char *)src + size - 1;dst = (char *)dst + size - 1;while (size--){*(char *)dst-- = *(char *)src--;}}return dst_;}char * dlut_strchr(const char *str, int v){while (*str && (int)*str != v)str++;return (char *)str;}/*you need know '\0' and '\0' is equal too*/int dlut_stricmp(const char *buf1, const char *buf2){while ((DLUT_TO_LOWER(*buf1)) == (DLUT_TO_LOWER(*buf2))&& *buf1 && *buf2){buf1++;buf2++;}return (int)(*buf1 - *buf2);}int dlut_strcoll(const char *buf1, const char *buf2){while (*buf1 == *buf2){buf1++;buf2++;}return *buf1 - *buf2;}int dlut_stricoll(const char *buf1, const char *buf2){while ((DLUT_TO_LOWER(*buf1)) == (DLUT_TO_LOWER(*buf2))&& *buf1 && *buf2){buf1++;buf2++;}return (int)(*buf1 - *buf2);}int dlut_strncoll(const char *buf1, const char *buf2, unsigned int size){while (size-- && *buf1 == *buf2 && *buf1 && *buf2){buf1++;buf2++;}return *buf1 - *buf2;}int dlut_strnicoll(const char *buf1, const char *buf2, unsigned int size){while (size-- && *buf1 && *buf2 && ((DLUT_TO_LOWER(*buf1)) == (DLUT_TO_LOWER(*buf2)))){buf1++;buf2++;}return *buf1 - *buf2;}unsigned int dlut_strcspn(const char *buf1, const char *buf2){const char *start;int count = 0;while (*buf2){start = buf1;count = 0;while (*start){if (*start == *buf2)return count;else{start++;count++;}}buf2++;}return count;}char * dlut_strdup(const char *str){char *dup;dup = (char *)malloc(dlut_strlen(str));dlut_strcpy(dup, str);return dup;}char * dlut_strerror(const char *str){return 0;}char * dlut_strlwr(char *str){char *start = str;while (*str){if ((*str >= 'A') && (*str <= 'Z')){*str = *str + 'a' - 'A';}str++;}return start;}char * dlut_strncat(char *dst, const char *src, unsigned int size){char *start = dst;while (*dst)dst++;while (size-- && *dst){*dst++ = *src++;}*dst = '\0';return start;}int dlut_strncmp(const char *buf1, const char *buf2, unsigned int size){while (--size && *buf1 && *buf2 && *buf1 == *buf2){buf1++;buf2++;}return *buf1 - *buf2;}int dlut_strnicmp(const char *buf1, const char *buf2, unsigned int size){while (--size && *buf1 && *buf2 && ((DLUT_TO_LOWER(*buf1)) == (DLUT_TO_LOWER(*buf2)))){buf1++;buf2++;}if (((DLUT_TO_LOWER(*buf1)) == (DLUT_TO_LOWER(*buf2))))return 0;elsereturn *buf1 - *buf2;}char * dlut_strncpy(char *buf1, const char *buf2, unsigned int size){char *start = buf1;while (size-- && *buf2){*buf1++ = *buf2++;}*buf1 = '\0';return start;}char * dlut_strnset(char *str, int v, unsigned int size){char *start = str;while(size-- && *str){*str++ = (char)v;}return start;}char * dlut_strpbrk(const char *buf1, const char *buf2){char *start;while (*buf2){start = (char *)buf1;while (*start){if (*start == *buf2){return start;}start++;}buf2++;}return start;}char * dlut_strrchr(const char *str, int v){const char *high = str;while (*high)high++;--high;while (high != str - 1){if (*high == (char)v)return (char *)high;elsehigh--;}return 0;}char * dlut_strrev(char *str){char *start = str;char *low = str;char *high = str;char c;while (*high)high++;--high;while (low < high){c = *low;*low++ = *high;*high-- = c;}return start;}/* * map有32个字节。就是256个BIT，可把map看成是一个2维数组[32][8]，每个ASCII码（设为c）有8BIT，把它分为2部分，低3位构成下标j（通过c & 7得到），高5位构成下标i（通过c>>3得到），这样在map[[i][j]中置1代表该字符存在。算法中先根据control构成map，然后把string中每个字符用同样方法计算出i和j，如果map[i][j]为1，则count加1 。 * */unsigned int dlut_strspn(const char *buf1, const char *buf2){unsigned int count = 0;const char *buf1_ = buf1;const char *buf2_ = buf2;char map[32];for (count = 0; count != 32; count++)map[count] = 0;while (*buf2_){map[*buf2_ >> 3] |= (1 << (*buf2_ & 7));buf2_++;}if (*buf1){count = 0;while ((map[*buf1_ >> 3] & (1 << (*buf1_ & 7))) && *buf1_){count++;buf1_++;}return count;}return 0;}char * dlut_strstr(const char *buf1, const char *buf2){char *buf1_;char *buf2_;char *start;while(*buf1){start = (char *)buf1;buf1_ = (char *)buf1;for (buf2_ = (char *)buf2; *buf2_; buf2_++){if (*buf1_ == *buf2_){if (*(buf2_ + 1) == '\0'){return start;}else{buf1_++;}}elsebreak;}buf1++;}return 0;}char * dlut_strtok(char *str, const char *delim){static char *reserved;char *start;if (str == 0)str = reserved;if (str == 0)return 0;start = str;while (*str){if (*delim && *delim == *str){*str = '\0';reserved = str + 1;return start;}str++;}reserved = 0;return start;}char * dlut_strupr(char *str){char *start = str;if (str == 0)return 0;while (*str){if (*str >= 'a' && *str <= 'z'){*str = *str - 'a' + 'A';}str++;}return start;}int dlut_bcmp(const void *buf1, const void *buf2, unsigned int size){char *buf1_ = (char *)buf1;char *buf2_ = (char *)buf2;while (size-- && *buf1_ == *buf2_){buf1_++;buf2_++;}return *buf1_ - *buf2_;}void dlut_bcopy(const void *src, void *dst, unsigned int size){char *src_ = (char *)src;char *dst_ = (char *)dst;while (size--){*dst_++ = *src_++;}return;}void dlut_bzero(void *str, unsigned int size){char *str_ = (char *)str;while (size--){*str_++ = 0;}return;}