How to check if C string is empty

Question

I\'m writing a very small program in C that needs to check if a certain string is empty. For the sake of this question, I\'ve simplified my code:

#include 

        

Answer 1

The shortest way to do that would be:

do {
    // Something
} while (*url);

Basically, *url will return the char at the first position in the array; since C strings are null-terminated, if the string is empty, its first position will be the character '\0', whose ASCII value is 0; since C logical statements treat every zero value as false, this loop will keep going while the first position of the string is non-null, that is, while the string is not empty.

Recommended readings if you want to understand this better:

• C strings: https://www.tutorialspoint.com/cprogramming/c_strings.htm
• C arrays: https://www.tutorialspoint.com/cprogramming/c_arrays.htm
• Relation between arrays and pointers: https://www.programiz.com/c-programming/c-pointers-arrays
• Logical operators: https://www.tutorialspoint.com/cprogramming/c_logical_operators.htm