Program stops when inputing a variable

Question

This is literally my first lines of code in C, so it's really basic.

The code is this:

#include<stdio.h>

int main()

{
    int l, b, ar, pr;

    printf("Enter the length of the rectangle");
    scanf("%d", l);
    
    printf("Enter the breadth of the rectangle");
    scanf("%d", b);

    ar = l * b;
    pr = 2 * (l + b);

    printf("\n Area of Rectangle is: %d", ar);
    printf("\n Perimeter of Rectangle is: %d", pr);

}

It starts running properly, outputs "Enter the length of the rectangle", but when I input a number, it just stops and I don't get to input the second value.

What am I missing?

You need to pass a pointer to a variable to the scanf so it can fill it with the input: scanf("%d", l);, scanf("%d", &b);. OT: Don't use l as a variable name as it can be confused with I or 1 — Eugene Sh.
– Eugene Sh., Commented May 20, 2021 at 13:27

MikeCAT · Accepted Answer · 2021-05-20 13:27:39Z

2

You have to pass pointers to the variables to get the values instead of the values in the variables.

You should use unary & operators to get pointers like this:

scanf("%d", &l);

Note that you don't need & to read strings because arrays are automatically converted to pointers to the first element (except for some cases, including when used as an operand of unary & operator).

char str[10];
scanf("%9s", str);

answered May 20, 2021 at 13:27

MikeCAT

75.1k11 gold badges50 silver badges71 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vad Sim · Accepted Answer · 2021-05-20 15:54:12Z

0

Corrected code

#include<stdio.h>

int main()

{
    int l, b, ar, pr;

    printf("Enter the length of the rectangle");
    scanf("%d", &l);
    
    printf("Enter the breadth of the rectangle");
    scanf("%d", &b);

    ar = l * b;
    pr = 2 * (l + b);

    printf("\n Area of Rectangle is: %d", ar);
    printf("\n Perimeter of Rectangle is: %d", pr);
}

answered May 20, 2021 at 15:54

Vad Sim

31610 silver badges21 bronze badges

Collectives™ on Stack Overflow

Program stops when inputing a variable

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related