Print line number incrementing with each input in C

Question

I would like to see line number in the console when it asks for input.

Something like:

1 foo
2 bar
3 baz

Here 1 was shown in the prompt and I enter any input and hit enter Then the next number shows up and I do the same.

Any simple help for this in C for a beginner?

Have a counter variable and increment it with every input you ask for. You'll then print it explicitly with every new input, something like: `unsigned int n = 0; for(;;) { /*... */ printf("%u", ++n); /* read input */ }` — Aconcagua, Jun 19 '21 at 09:42

score 2 · Accepted Answer · answered Jun 19 '21 at 09:55

2

This will might help you.

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <string.h>

int main() {
    int lineNo = 0;
    char name[256];

    do {
        printf("%d ", ++lineNo);
        scanf("%s", name);

    } while (strlen(name) > 0);

    return 0;
}

answered Jun 19 '21 at 09:55

Denis Turgenev

138
1
9

3

You should specify the max size of the string to input in `scanf` in the format string, otherwise it's no better than `gets`. – mediocrevegetable1 Jun 19 '21 at 10:01
yes, scanf_s("%s", name, 256); is more stable. – Denis Turgenev Jun 19 '21 at 10:10
both are the same "stable". One is not as safe as another – 0___________ Jun 19 '21 at 10:15
2

To read a _line_ of user input, best to use `fgets()`. – chux - Reinstate Monica Jun 19 '21 at 13:04
`#define _CRT_SECURE_NO_WARNINGS` is MSVC-specific stuff. You shouldn't include in a general answer, for instance it is entirely meaningless if using GCC. – Aconcagua Jun 19 '21 at 14:43
regarding: `scanf("%s", name);` when the user enters nothing more than a the contents of `name` will not change. the result will be a 'forever' loop – user3629249 Jun 21 '21 at 23:43
1

I don't know . What is ? – user2656 Jun 22 '21 at 04:38
1

I certainly would but I don't have enough reputation (15). – user2656 Jun 22 '21 at 07:10
1

I'd need 2 more. Its 13 now. – user2656 Jun 22 '21 at 07:14

score 0 · Answer 2 · answered Jun 19 '21 at 10:22

0

I think I tried the easiest way I know for this. You can do this with the help of a 2D array. Following is the code for this:

#include<stdio.h>
main()
{
char arr[3][1];
int i,j;
for(i=0;i<3;i++){
    for(j=0;j<1;j++){
        printf("%d ",i+1);
        scanf("%s",&arr[i][j]);
        }
}

}

You can change the size of the array as per the number of inputs you want. This code is taking 3 inputs, you can change it to as per your input needs.

answered Jun 19 '21 at 10:22

LucyRage

28
6

`char arr[3][1];` is too small and leads to undefined behavior with `scanf("%s",&arr[i][j]);`. The application of `for(j=0;j<1;j++){` is amiss as no need to loop for each character. – chux - Reinstate Monica Jun 19 '21 at 13:07

Print line number incrementing with each input in C

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