运行出来时乱码
#include <iostream>
using namespace std;

char *mystrncpy(char *str2, const char *str1, int n)
{
    int i = 0;
    char *dest = str2;
    while(*str1 != '\0' && i < n)
    {
        *str2++ = *str1++;
        i++;
    }
    return dest;
}

void main()
{
    char *p = "abcde";
    char *q = new char(20);
    char *w = mystrncpy(q,p,3);
    cout << w << endl;
    system("pause");
}


为什么下面这段代码也是错的？
#include <iostream>
using namespace std;

void main()
{
    char *p = new char[20];
    char *q = "abcde";
    strncpy(p, q, sizeof(q));
    cout << p << endl;
    system("pause");
}


[ 本帖最后由 lateraware 于 2012-2-23 23:31 编辑 ]

没错 出乱码的原因就是没有 '\0'

是的 strlen这个用得好！呵呵

#include <iostream>
#include <cstdlib>
using namespace std;

char *mystrncpy(char *dest, const char *src, size_t count)
{
    char *tmp = dest;
    dest[count] = '\0';
    while (count) {
        if ((*tmp = *src) != '\0')
            src++;
        tmp++;
        count--;
    }
    return dest;
 }

int main()
{
    char *p = "abcde";
    char *q = new char[20];
    char *w = mystrncpy(q,p,3);
    cout << w << endl;
    system("pause");
    return 0;
}