How to convert a string to integer in C?

Question

I am trying to find out if there is an alternative way of converting string to integer in C.

I regularly pattern the following in my code.

char s[] =         


        

Answer 1

int atoi(const char* str){
    int num = 0;
    int i = 0;
    bool isNegetive = false;
    if(str[i] == '-'){
        isNegetive = true;
        i++;
    }
    while (str[i] && (str[i] >= '0' && str[i] <= '9')){
        num = num * 10 + (str[i] - '0');
        i++;
    }
    if(isNegetive) num = -1 * num;
    return num;
}