#include "stdafx.h"#include <stdio.h>#include <stdlib.h>#include <string.h>#define TRUE   1#define FALSE  0#define BIG    1#define EQUAL  0#define SMALL -1unsigned int strlenth(char *s)  /* 获取字符串长度 */{    unsigned int lenth = 0;    if (!s)        return 0;    while (‘\0‘ != s[lenth])    {        lenth++;    }    return lenth;}void strcopy(char **target, char *source)  /* 字符串拷贝 */{    unsigned int i = 0;    unsigned int length = 0;    char *pTmp = *target;     length = strlenth(source);    while(‘\0‘ != source[i])    {        pTmp[i] = source[i];        i++;    }    pTmp[i] = ‘\0‘;}int strcompare(char *s, char *t)  /* 字符串比较，s>t，则返回1；s=t，则返回0；s<t，则返回-1 */{    unsigned int uiIndex = 0;    unsigned int uiLenOfS = strlenth(s);    unsigned int uiLenOfT = strlenth(t);    if (0 != uiLenOfS && 0 == uiLenOfT)        //如果s字符数不为0，而t字符数为0，则返回1    {        return BIG;    }    else if (0 == uiLenOfS && 0 != uiLenOfT)//如果s字符数为0，而t字符数不为0，则返回-1    {        return SMALL;    }    else if (0 == uiLenOfS && 0 == uiLenOfT)//如果s和t字符数都为0，则返回0。字符数为0的情况有空串或字符串指针为空    {        return EQUAL;    }    else                                    //s和t的字符数都不为0    {        /* 同时遍历两个字符串，只要有一个扫描完，就退出 */        while (‘\0‘ != s[uiIndex] && ‘\0‘ != t[uiIndex])        {            if (s[uiIndex] > t[uiIndex])            {                return BIG;            }            else if (s[uiIndex] < t[uiIndex])            {                return SMALL;            }            else             {                ;            }            uiIndex++;        }        /* 扫描结束后，哪个字符串没扫描完，则说明这个字符串大；如果都扫描完了，说明相等 */        if (‘\0‘ != s[uiIndex] && ‘\0‘ == t[uiIndex] )        {            return BIG;        }        else if (‘\0‘ == s[uiIndex] && ‘\0‘ != t[uiIndex] )        {            return SMALL;        }        else        {            return EQUAL;        }    }}void strcombine(char **s, char *t)  /* 字符串连接，将字符串t接到s后面，x为连接后的新串 */{    unsigned int uiLen = 0;    char *pTmp = *s;    if (NULL == s || NULL == t)    {        return;    }    uiLen = strlenth(pTmp) + strlenth(t);    memcpy(pTmp + strlenth(pTmp), t, strlenth(t));}void strcatch(char *s, unsigned int index, unsigned int lenth, char **t)  /* 字符串截取，从第index个字符开始，截取lenth长度的字符串，并输出到字符串t */{    char *pTmp = *t;    char *pSrc =http://www.mamicode.com/ s;    if (NULL == s)    {        return;    }    if (index < 0 || lenth <= 0 || index + lenth >= strlenth(s))    {        return;    }    while (index--)    {        pSrc++;    }    memcpy(pTmp, pSrc, lenth);}bool strsubstr(char *s, char *sub)  /* 字符串子串查找，如果子串sub在s中存在，则返回1，否则返回0 */{    unsigned int uiIndexOfS = 0;    unsigned int uiIndexOfSub = 0;    unsigned int uiLenOfS = strlenth(s);    unsigned int uiLenOfSub = strlenth(sub);    if (NULL == s || NULL == sub)    {        return FALSE;    }    if (uiLenOfS < uiLenOfSub)        //如果子串长度大于原串，则返回0    {        return FALSE;    }    while (‘\0‘ != s[uiIndexOfS])    {        if (s[uiIndexOfS] == sub[0])        {            while (‘\0‘ != sub[uiIndexOfSub])            {                if (s[uiIndexOfS] != sub[uiIndexOfSub])                {                    return FALSE;                }                uiIndexOfS++;                uiIndexOfSub++;            }            if (‘\0‘ == sub[uiIndexOfSub])            {                return TRUE;            }        }        uiIndexOfS++;    }    if (‘\0‘ != sub[uiIndexOfSub])    {        return FALSE;    }    else     {        return TRUE;    }}int main(){    char str1[] = "Hello";    char str2[] = " World";    char str3[] = "Hello";    char *str4 = (char*)malloc(100);    if (!str4)        return 0;    memset(str4, 0, 100);        char *str5 = (char*)malloc(100);    if (!str5)        return 0;    memset(str5, 0, 100);    strcopy(&str5, str1);    strcombine(&str5, str2);    strcatch(str5, 0, 5, &str4);    printf("str5 = %s\n", str5);    printf("The length of str1 is %u\n", strlenth(str1));    printf("strcompare(str1, str2) = %d\n", strcompare(str1, str2));    printf("strcompare(str1, str3) = %d\n", strcompare(str1, str3));    printf("strsubstr(str5, str1) = %d\n", strsubstr(str5, str1));    printf("Call strcatch(str5, 0, 5, &str4), str4 = %s\n", str4);}