Question

What I am trying to do is to write a program wherein you input two digits and
then they are converted into words which gets printed. The problem is that this program
hangs after you input the two digits and I have no idea why. Any and all help is appreciated.
I am a beginner and all I can use to solve this is basically if and switch. Thanks again.

#include <stdio.h>

int main (void)
{
    int firstNum, secondNum;

    printf("Enter a two digit number: ");
    scanf("%d%d", &firstNum,&secondNum);

    if (firstNum == 1 && secondNum == 0){
            printf("You entered the number ten\n");}
    if (firstNum == 1 && secondNum == 1){
                printf("You entered the number eleven\n");}
    if (firstNum == 1 && secondNum == 2){
                printf("You entered the number twelve\n");}
    if (firstNum == 1 && secondNum == 3){
                printf("You entered the number thirteen\n");}
    if (firstNum == 1 && secondNum == 4){
                printf("You entered the number forteen\n");}
    if (firstNum == 1 && secondNum == 5){
                printf("You entered the number fifteen\n");}
    if (firstNum == 1 && secondNum == 6){
                printf("You entered the number sixteen\n");}
    if (firstNum == 1 && secondNum == 7){
                printf("You entered the number seventeen\n");}
    if (firstNum == 1 && secondNum == 8){
                printf("You entered the number eighteen\n");}
    if (firstNum == 1 && secondNum == 9){
                printf("You entered the number nineteen\n");}
    switch(firstNum){
        case 2: printf("You entered the number twenty-");break;
        case 3: printf("You entered the number thirty-");break;
        case 4: printf("You entered the number forty-");break;
        case 5: printf("You entered the number fifty-");break;
        case 6: printf("You entered the number sixty-");break;
        case 7: printf("You entered the number seventy-");break;
        case 8: printf("You entered the number eighty-");break;
        case 9: printf("You entered the number ninty-");break;
    }
    switch (secondNum){
        case 1: printf("one.\n");break;
        case 2: printf("two.\n");break;
        case 3: printf("three.\n");break;
        case 4: printf("four.\n");break;
        case 5: printf("five.\n");break;
        case 6: printf("six.\n");break;
    }
    return 0;
}

Answer 1

Your program “hangs” because it is waiting for a second number.

Instead of 42ENTER, type 42fooENTER.

---

You need to verify the return value from scanf()

if (scanf("%d%d", &firstNum, &secondNum) != 2) {
    fprintf(stderr, "Oops, the scanf didn't read 2 numbers.\n");
} else {
    /* continue with program */
    /* you might as well see what scanf got from the input */
    printf("scanf got the values %d and %d.\n", firstNum, secondNum);
}