CODEWITHSUNDEEP
c
brainsfrying
brainsfrying

Reputation: 339

How can i read a line of numbers from stdin & compute their average?

How may I count & extract a number of elements from stdin?

For instance, len() is easily available in Python, but not in C?

Im trying to compute an average, when user enters for eg: 1 3 5 7 8 10 11 -1

I've tried the following:

while (user_input != -1)
{
    total   += user_input;
    scanf ("%d", &user_input);

    //cannot work               
    average = total /  ...
}       
printf("Average = %f\n", average);

Upvotes: 2

Views: 3995

Answers (2)

Aniket Inge
Aniket Inge

Reputation: 25705

You'll have to maintain a counter to do what you're trying to do. its just int counter = 0; and in the loop: counter++

int counter = 0;
while (user_input != -1)
{
    total   += user_input;
    counter ++;
    scanf ("%d", &user_input);
}       
average = total / counter;
printf("Average = %f\n", average);

obviously, you'll have to check if scanf() returned atleast 1

--- EDIT --- the following program(that corresponds to the previous program) is VALID and works as required. People who do not understand how scanf() works, should stay the damn out:

#include <stdio.h>

int main(int argc, char *argv[])
{
   int total = 0;
   float average = 0.0f;
   int userinput = 0;
   int counter = -1;
   while(userinput != -1){
      counter ++;
      if(scanf("%d",&userinput) == 1 && userinput != -1){
         total += userinput;
      }
   }
   average = ((float)total/(float)counter);
   printf("Average = %f", average);
   return 0;
}

Input: 10 20 30 40 50 60 -1 Output: Average = 35

Upvotes: 1

Alok Save
Alok Save

Reputation: 206518

From your modified question & comments, it seems what you really want to do is read a line of input from the user and then extract numbers from that line of input.
The answer is you cannot do that using scanf, You need to use fgets to read the line from stdin and then you need to extract numbers from that read line. Here is a,
Quick sample program: 

#include<stdio.h>
int main()
{
    char line[1024], *beg, *end;
    long readvalue;
    while (fgets(line, sizeof(line), stdin)) 
    {
        beg = line;
        for (beg = line; ; beg = end) 
        {
            readvalue = strtol(beg, &end, 10);
            if (beg == end)
                break;
                printf("[%d]",readvalue);
        }
    }
    return 0;
}

Input: 

1 3 5 7 8 10 11 -1

Output: 

[1][3][5][7][8][10][11][-1]

Upvotes: 0

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