Taking continuous input from user in C

Question

I am working on a project where I have to take input from a user in the terminal in c until they input quit then I end the program. I realized I cant do this:

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

int main(int argc, char **argv){
    char *i;
    while(1){
        scanf("%s", i);

        /*do my program here*/
        myMethod(i);

    }

}

So my question is how can I go about taking this coninuous user input? Can I do it with loops or what else can I do?

Answer 1

First you have to allocate space for the string you are reading, this is normally done with a char array with the size of a macro. char i[BUFFER_SIZE] Then you read data into your buffer,fgets might be better than scanf for that. Finally you check your exit case, a strcmp with "quit".

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

#define BUFFER_SIZE BUFSIZ /* or some other number */

int main(int argc, const char **argv) {
    char i[BUFFER_SIZE];
    fgets(i, BUFSIZ, stdin);
    while (strcmp(i, "quit\n") != 0) {
        myMethod(i);
        fgets(i, BUFSIZ, stdin);
    }
}

Strings obtained with fgets are gurenteed null terminated

Answer 2

scanf() will return number of elements successfully read I will make use of it like below

#include<stdio.h>
#include<string.h>
int main()
{
   int a[20];
   int i=0;
   printf("Keep entering numbers and when you are done press some character\n");
   while((scanf("%d",&a[i])) == 1)
   {   
      printf("%d\n",a[i]);
      i++;
   }   

   printf("User has ended giving inputs\n");
   return 0;
}

Answer 3

You can use a do while loop:

do
{
    // prompts the user 
}
while (valueGiven != "quit");

Answer 4

using do-while loop. 

   char *i = null;
   char ch = 'a';/
   do{
    scanf("%s", &i);

    /*do my program here*/
    myMethod(i);
    printf("Do you want to continues.. y/n");
    ch =  getchar();

    }while(ch != 'q');