while循环中字符串数组末尾的分段错误

Question

Here's part of my code

char **images; // An array of strings filled with valid data

while(*images)
{
    printf("input image = %s\n", *images);
    images++;
}

I'm expecting it to exit the loop when the end of the array is reached but it still goes inside the loop and crashes. Please suggest how to fix this issue. The number of elements in the array is not fixed.

Answer 1

The code will not know how to stop since the while loop is always true, ie not zero. Even if you run past the end of the array into unmarked address space the code will keep going and then segfault as you suggest.

You should always close off string data with a marker such as "\\0" and perform a check in the while loop ie:

while ( strcmp(*images, "\0") != 0 )

or you should know the size of the **images array and stop after reading the last item. For this reason its probably better to use a for loop instead of a while loop. The strcmp version above is much less efficient. The for loop should be very efficient.