strcpy和strncpy

When we use strcpy (), if there is space space considered when the source string is greater than the target string is what happens: The following I made a simple case:

#include <stdio.h>
#include <string.h>

int main() {
    char *obj="Hello World!";
    char dest[5]={0};
    
    
    strcpy(dest,obj);
    printf("%s\n",dest);

    return 0;
}

When using gcc compiler implementation, there have been mistakes which is obviously very dangerous, so libc there a more cautious string copy function strncpy (), continue to make a case:

#include <stdio.h>
#include <string.h>

int main() {
    char *obj="Hello World!";
    char dest[5]={0};

    strncpy(dest,obj,sizeof(dest)-1);
    printf("%s\n",dest);

    return 0;
}

After compiling the results of the implementation of the output is: hell did not appear the mistakes, so when the need to use the string copy when the priority use strncpy () is a more good choice There is a need to pay attention to detail, we need to leave. a space to store the units '\ 0', so in the third argument I use sizeof (dest) -1, where if you do not -1, the segment still an error, because the string is \ 0 marks the end , so be sure to leave a space.