Difference between using atoi and scanf

I have a question, whats the difference between (1) using atoi to convert a 'char number' (number used in a char variable) into a int variable , (2) and just using scanf to read the int directly instead of having to get it first as a char variable and then having to convert it to int variable? Example:

First part of program (both examples start with this):

Code:

---

#include <stdio.h>
#include <stdlib.h>

int getval(void);

void main()
{
        int age,weight,area;
        float iq;

        printf("Program to calculate your IQ.
");
        printf("Enter your age:");
        age=getval();
        printf("Enter your weight:");
        weight=getval();
        printf("Enter your area code:");
        area=getval();

        iq=(float)(age*weight)/area;
        printf("This computer estimates your IQ to be %f.
",iq);
}

---

Now here are the 2 examples (the follow the first part of the program):

(1)

Code:

---


int getval(void)
{
        char input[20];
        int x;

        gets(input);
        x=atoi(input);
        return(x);
}

---

(2)

Code:

---


int getval(void)
{
        int x;

        scanf("%i",&x);
        return(x);
}

---

Hope you underestand what I am trying to say. Thanks!

There is no difference. They will both work if the user enters correct information. You may not want to use gets()'s though, use fgets()'s

ex: fgets(input, sizeof(input), stdin);

There is an advantage of using the atoi family because one can scan the string for digits and spit out other types. Users don't always follow instructions. :D

The thing to watch out for is using the appropriate conversion function for the size of the anticipated number.

James00: Read and read. :)

Thanks a lot!!! Hammer, your guide is awesome, I now know exactly what each function is. A million thanks!!! :D