8.1.3

#include <iostream>
#include <cmath>
#include <string.h>


using namespace std;

char* strcat( char* dest, const char* src)
{
    int lengthDest=strlen(dest);
    int length=strlen(dest)+strlen(src);
    for (int i=lengthDest,j=0;i<length;i++,j++)
    {
        dest[i]=src[j];
    }
    dest[length]=0;
    return dest;
}

int main()
{
    char str[100]="hello ";
    strcat(str,"world");
    cout<<str;
    return 0;
}