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#include <stdio.h>

int main() {

    char operator;
    int a,b;    

    printf("Enter 1st operands: ");
    scanf("%d",&a);    

    printf("Enter 2nd operands: ");
    scanf("%d",&b);

   //here after taking the input of integers the code skips to default without 
//taking the character input 

    printf("Enter an operator (+, -, *,/): ");
    scanf("%c", &operator);

    switch(operator)
    {
        case '+':
            printf("%d+ %d = %d",a, b, a + b);
            break;

        case '-':
            printf("%d- %d = %d",a, b, a - b);
            break;

        default:
            printf("Error! operator is not correct");
    }

    return 0;
}
Jabberwocky
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Alinoor Rahman
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2 Answers2

2

scanf("%c", &operator); actually reads the newline character that remains on the input stream.

The remedy - scanf(" %c", &operator); - note the space, is the idiomatic way of getting round this.

Bathsheba
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  • Can you please elaborate? or give any descriptive links? I didn't properly understand the matter. tia – Alinoor Rahman Feb 06 '17 at 15:26
  • Get your favourite debugger out. Look at `operator` before the `switch` block. Bet you a quid it's 10, corresponding to what happens when you press your Return key on the keyboard. – Bathsheba Feb 06 '17 at 15:27
1

Write

scanf(" %c", &operator);
      ^^^^

Otherwise control characters will be stored in the object.

From the function description in the C Standard (7.21.6.2 The fscanf function)

5 A directive composed of white-space character(s) is executed by reading input up to the first non-white-space character (which remains unread), or until no more characters can be read.

Vlad from Moscow
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