I need to read all integers, mathematical operators, and characters in a string

Question

I have a string which may contain either single integers between 0-9 or mathematical operators (+, -, *, /).

Basically, I need to read in all characters / numbers. I am checking if the character is either +,-,* or /. If not, then I know it is either a number or an invalid character. I am using atoi to convert it to an integer. atoi will return 0 in both cases: if the integer is a 0 OR if it was an invalid character.

How else can I make this distinction?

Answer 1

Check each character with standard isdigit() function before using atoi