拷贝字符串---第十七天

1.myStrnpy(str,p,9);  //把p地址的前9位字符串拷贝到str这边来

#include <stdio.h>


char* myStrcpy(char *des,char *src)  //目标地址，原地址
{
if(des == NULL || src == NULL)
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0'){
*des = *src;
des++;
src++;
}
*des = '\0';

return bak;
}

char* myStrcpy2(char *des,char *src)  //目标地址，原地址
{
if(des == NULL || src == NULL)
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0'){
*des++ = *src++;
}
*des = '\0';

return bak;
}

char* myStrcpy3(char *des,char *src)  //目标地址，原地址
{
if(des == NULL || src == NULL)
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while( (*des++ = *src++)!='\0'){   //赋值归赋值，是可以多一层判断的
//赋值加判断 可以一起  
}
*des = '\0';
return bak;
}

char* myStrnpy(char *des,char *src,int count)  //目标地址，原地址
{
if(des == NULL || src == NULL)  //判断目的地址和原地址不等于0
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0' && count>0){
*des++ = *src++;
count--;
*des = '\0';
}

if(count >0)   
{
while(count > 0)
{
count--;
*des++ = '\0';  //给多出来的位置赋值
}
}
*des = '\0';

return bak;
}


int main()
{
char str[128] = {'\0'};
char *p = "caoshupei handsome";
myStrcpy(str,p);  //把p拷贝到str这边来
puts(str);

myStrcpy2(str,p);
puts(str);

myStrcpy3(str,p);
puts(str);

myStrnpy(str,p,9);
puts(str);
return 0;
}

2. 断言：assert ( ) 判断括号内其值为假（为0）则终止程序

#include "assert.h"

void assert(int experssion);

输出expression：在哪里错误

#include <stdio.h>
#include "assert.h"


char* myStrcpy(char *des,char *src)  //目标地址，原地址
{
assert(des!= NULL && src != NULL);

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0'){
*des = *src;
des++;
src++;
}
*des = '\0';

return bak;
}

char* myStrcpy2(char *des,char *src)  //目标地址，原地址
{
if(des == NULL || src == NULL)
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0'){
*des++ = *src++;
}
*des = '\0';

return bak;
}

char* myStrcpy3(char *des,char *src)  //目标地址，原地址
{
if(des == NULL || src == NULL)
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while( (*des++ = *src++)!='\0'){   //赋值归赋值，是可以多一层判断的
//赋值加判断 可以一起  
}
*des = '\0';
return bak;
}

char* myStrnpy(char *des,char *src,int count)  //目标地址，原地址
{
if(des == NULL || src == NULL)  //判断目的地址和原地址不等于0
{
return NULL;
}

char *bak = des;  //目标地址赋值给备份地址
while(*src !='\0' && count>0){
*des++ = *src++;
count--;
*des = '\0';
}

if(count >0)   
{
while(count > 0)
{
count--;
*des++ = '\0';  //给多出来的位置赋值
}
}
*des = '\0';

return bak;
}


int main()
{
char str[128] = {'\0'};

char *p = "caoshupei handsome";
char *pstr = NULL;
myStrcpy(pstr,p);  //把p拷贝到str这边来

myStrcpy(str,p);  //把p拷贝到str这边来
puts(str);

myStrcpy2(str,p);
puts(str);

myStrcpy3(str,p);
puts(str);

myStrnpy(str,p,9);
puts(str);
return 0;
}

        

原文地址：https://blog.csdn.net/m0_74156325/article/details/137697672

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