Read Multiple Inputs from User using a Loop in C

In C, we can read multiple inputs from the user efficiently using loops such as for, while, or do-while. By using a loop, we avoid redundant code and allow the user to input multiple values dynamically. This approach is commonly used in programs that require user-defined lists, calculations, or data storage.

Examples of Reading Multiple Inputs

1. Reading Multiple Integers Using a for Loop

In this example, we will ask the user to enter 5 integers and store them in an array using a for loop.

main.c

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#include <stdio.h>

int main() {
    int numbers[5];

    // Using a for loop to take 5 inputs
    printf("Enter 5 integers:\n");
    for (int i = 0; i < 5; i++) {
        scanf("%d", &numbers[i]);
    }

    // Displaying the entered numbers
    printf("You entered: ");
    for (int i = 0; i < 5; i++) {
        printf("%d ", numbers[i]);
    }

    return 0;
}

Explanation:

  1. We declare an integer array numbers[5] to store 5 integers.
  2. We use a for loop to iterate 5 times and read user inputs using scanf("%d", &numbers[i]).
  3. We then use another for loop to print the stored values.

Output:

Enter 5 integers:
10 20 30 40 50
You entered: 10 20 30 40 50

2. Reading Multiple Inputs Until User Enters Zero

In this example, we will allow the user to keep entering numbers until they enter zero. We will use a while loop for this.

main.c

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#include <stdio.h>

int main() {
    int number;

    // Using while loop to take inputs until 0 is entered
    printf("Enter numbers (enter 0 to stop):\n");
    while (1) {
        scanf("%d", &number);
        if (number == 0) {
            break;
        }
        printf("You entered: %d\n", number);
    }

    return 0;
}

Explanation:

  1. We declare an integer variable number to store user input.
  2. A while(1) loop is used to continuously take inputs.
  3. If the user enters 0, we use break to exit the loop.
  4. Otherwise, we print the entered number.

Output:

Enter numbers (enter 0 to stop):
5
You entered: 5
8
You entered: 8
0

3. Reading Multiple Strings Using a for Loop

In this example, we will read multiple strings from the user and store them in an array of strings.

main.c

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#include <stdio.h>

int main() {
    char names[3][20];

    // Using for loop to take multiple string inputs
    printf("Enter 3 names:\n");
    for (int i = 0; i < 3; i++) {
        scanf("%s", names[i]);
    }

    // Displaying the entered names
    printf("You entered:\n");
    for (int i = 0; i < 3; i++) {
        printf("%s\n", names[i]);
    }

    return 0;
}

Explanation:

  1. We declare a 2D character array names[3][20] to store 3 strings, each up to 20 characters.
  2. A for loop is used to take 3 string inputs using scanf("%s", names[i]).
  3. Another for loop prints the stored names.

Output:

Enter 3 names:
Arjun
Ram
Priya
You entered:
Arjun
Ram
Priya

Conclusion

In this tutorial, we explored different ways to read multiple inputs from the user using loops in C:

  1. for Loop: Used when we know how many inputs we need.
  2. while Loop: Useful when the number of inputs is unknown (e.g., stopping on a condition).
  3. Reading Strings: Demonstrated how to take multiple string inputs.