MyStrlen, MyStrcmp, MyReverse,MyStrcpy,MyStrncpy,Merge,Change

来源：互联网发布：李善姬在韩国地位知乎编辑：程序博客网时间：2024/04/29 08:59
#include <iostream>#include <cstring>#include <cassert>using namespace std;int MyStrlen(char* a)  //strlen(a){    int i=0;    while(a[i]!='\0')    {        i++;    }    return i;}int MyStrcmp(char* s, char* t){    assert(s!=NULL);    assert(t!=NULL);    while(*s && *t && (*s==*t))    {        s++;        t++;    }    if(*s>*t)    {        return 1;    }    else if(*s<*t)    {        return -1;    }    else    {        return 0;    }}void MyReverse(char* a)  //头尾交换{    int size= MyStrlen(a);  // strlen(a);    for(int i=0; i<size/2; i++)    {        char temp=a[i];        a[i]=a[size-1-i];        a[size-1-i]=temp;    }}char* MyStrcpy(char* dest, char* src){    assert(dest!=NULL);    assert(src!=NULL);    int i=0;    for(; src[i]!='\0'; i++)    {        dest[i]=src[i];    }    dest[i]='\000';    return dest;}char* MyStrncpy(char*dest, char* src, int pos){    assert(dest!=NULL);    assert(src!=NULL);    int SizeSrc=MyStrlen(src);    if(SizeSrc>=pos)    {        int i=0;        for(; i<pos; i++)        {            dest[i] =src[i];        }        return dest;    }    else    {        int i=0;        for(;i<SizeSrc; i++)        {            dest[i]=src[i];        }        //dest[i]='\0';        return dest;    }}char* Merge(char* dest, char* src)//strcat{    int i=0;    int j=0;    while(dest[i] !='\0')    {        i++;    }    while(src[j] !='\0')    {        dest[i] = src[j];        i++;        j++;    }    dest[i]='\0';    return dest;}char* Change(char* a, int pos) // 指定位置前后对换位  pos=3 abc defg -> defg abc{    char* temp=new char[pos+1];    MyStrncpy(temp, a, pos);    temp[pos]='\0';    MyStrncpy(a,a+pos,7-pos);    MyStrncpy(a+7-pos,temp,pos);    delete [] temp;    return a;}int main(){    char a[]="abcdefg";    cout<<"size of the char a[]: ";    cout<<MyStrlen(a)<<endl;    cout<<"Initial char a[]: ";    cout<<a<<endl;    MyReverse(a);    cout<<"after reverse char a[]: ";    cout<<a<<endl;    cout<<"after shabi   dadong: ";    cout<<Change(a,4)<<endl;    return 0;}
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