Question

I wrote a function which takes in a string and simply encodes the string (compresses if you will) the string in this format: input = aassda , output = 2a2s1d1a. My problem is if I input a string that is 47 characters or longer I get a seg fault. I attached the function bellow. I started C about a week ago so please bear with me =/

Edit: Any improvements suggestions would be nice also. I know I could make the code much more efficient but coming from a small background in python I decided to do it in the most direct way possible.

Answer 1

string is just a junk pointer. It is never set and it is never associated with any memory. You either need to malloc() some memory for string (don’t forget to free() it when you’re done!), or you need to make it an array. That is, your two choices are:

Using malloc()/free():

int main()
{
    char* string = malloc(51); // Room for 51 chars (50 letters and 1 null terminating character)

    printf("Please input a string of at most 50 chars: ");
    scanf("%s", string);
    lame_function(string);

    free(string);
}

Using arrays:

int main()
{
    char string[51]; // Room for 51 chars (50 letters and 1 null terminating character)

    printf("Please input a string of at most 50 chars: ");
    scanf("%s", string);
    lame_function(string);
}