C assign string from argv[] to char array

Question

I have the following code which reads an file name from the command line and opens this file:

#include 
#include 
int main(int         


        

Answer 1

You must copy the string into the char array, this cannot be done with a simple assignment.

The simplistic answer is strcpy(filename, argv[1]);.

There is a big problem with this method: the command line parameter might be longer than the filename array, leading to a buffer overflow.

The correct answer therefore:

if (argc < 2) {
    printf("missing filename\n");
    exit(1);
}
if (strlen(argv[1]) >= sizeof(filename)) {
    printf("filename too long: %s\n", argv[1]);
    exit(1);
}
strcpy(filename, argv[1]);
...

You might want to output the error messages to stderr. As a side note, you probably want to choose English or German, but not use both at the same time ;-)