Checking user input in C

Question

I would like to ask: How to check user input , which is stored in array with another array, I have defined... Something like this: User will give input 10,20,5 and I need to check, if it is from this array {5,10,20,50}

Any help appreciated :). Thanks

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

int main ()
{
float bill;  
int notes[] = {100, 50, 20, 10, 5, 2, 1, 0.50, 0.20, 0.10, 0.05, 0.02, 0.01};
printf("Enter value of your bill: ");
scanf("%f",&bill);
if (bill<0 || bill>10000)
{
return -1;
}

else 
{
for (int i=0; i<8;i++)
{
if (bill!=notes[i])
    {
    break;
    }
    }
    }





   return 0;}

What do you mean user input that's stored in an array? Is the user a robot that speaks in arrays? — ProfOak
– ProfOak, Commented Mar 10, 2015 at 19:22
Nah,sorry for wrong interpretation. I just want to check user's input — JEl
– JEl, Commented Mar 10, 2015 at 19:24
do u want to check each one at a time or the 3 input or more — Setu Kumar Basak
– Setu Kumar Basak, Commented Mar 10, 2015 at 19:26
I'd terminate my notes[] array with 0. Rather than doing the for loop for(i=0;i<8;i++) I'd use for(i=0;notes[i];i++) — phil
– phil, Commented Mar 10, 2015 at 19:53

ProfOak · Accepted Answer · 2015-03-10 19:43:08Z

To get user input you must use the scanf() function. Here is an example, where it asks for three separate numbers.

#include <stdio.h>

int main(void) { 
    int one, two, three;
    printf("Enter first number: ");
    scanf("%d", &one);
    printf("Enter second number: ");
    scanf("%d", &two);
    printf("Enter third number: ");
    scanf("%d", &three);

    printf("one: %d, two: %d, three: %d\n", one, two, three);
    return 0;
}

Will produce the following:

Enter first number: 1
Enter second number: 2
Enter third number: 3
one: 1, two: 2, three: 3

Here is another way to use scanf, but the user must be more specific about how they answer the prompt.

#include <stdio.h>

int main(void) { 
    int one, two, three;
    printf("Enter three numbers separated by a comma: ");
    scanf("%d,%d,%d", &one, &two, &three);

    printf("one: %d, two: %d, three: %d\n", one, two, three);
    return 0;
}

Will produce the following:

Enter three numbers separated by a comma: 1,2,3
one: 1, two: 2, three: 3

UPDATE: Because you posted code that shows you know how scanf works.

To search through an array you must use a for loop.

#include <stdio.h>

int main(void) { 
    float n = 100;
    int numbers[] = {5, 10, 20, 50, 100, 200, 500};

    int i;
    for (i = 0; i < 7; i++) {
        if (n == numbers[i]) {
            printf("Matching index for %f at %d\n", n, i);
        }
    }

    return 0;
}

Setu Kumar Basak · Accepted Answer · 2015-03-10 19:54:12Z

0

#include<stdio.h>
int main(){
  int inp,i,j;
  int foo=0;
  int arr[]={5,10,20,30};
     for(j=0;j<3;j++){
       scanf("%d",&inp);
       for(i=0;i<4;i++)
       {
          if(inp == arr[i])
          {
              foo=1;
              break;
          }
       }
       if(foo==0)
        break;
   }

}

edited Mar 10, 2015 at 19:54

answered Mar 10, 2015 at 19:34

Setu Kumar Basak

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1 Comment

JEl Over a year ago

one more question: what if user input is 10 20 50 ? you know,like three numbers

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