CODEWITHSUNDEEP
c
Darlyn
Darlyn

Reputation: 4940

incrementing variable inside loops

Im new to C language , been doing in it for hour but i found strange behavior of loop iterations this code

int main(int argc, char** argv)
{
    int c;
    int big;
    int small;
    while(c=getchar())
    {
        if(c>='A' && c<='Z');
        big++;
        printf("%d",big);
    }
    printf("end");
}

should increment int big whenever there is a upper case character. But it always print big numbers like 5452 and so on , did i miss something about iteration in c language or there is a bug in my simple code?

Upvotes: 1

Views: 267

Answers (4)

Manos Nikolaidis
Manos Nikolaidis

Reputation: 22224

You need to initialize big and the other variables to 0 in your case :

int c = 0;
int big = 0;
int small = 0;

Otherwise these variables will contain "random" values. This is a form of undefined behaviour that you will encounter a lot in C/C++.

Also these lines in your code are probably not doing what you expect

if(c>='A' && c<='Z');
    big++;

There is an empty statement at the end of the if. Remove the semicolon :

if(c>='A' && c<='Z')
    big++;

An extra problem is printing big in the while loop. getchar() will return any character you type including space. printf("%d",big); will be executed every time you type a character not every time you type an upper case or non white space char. So if you type "A A" you will get "112" There are a few ways to sort this. One solution :

if (!isspace(c)) {
    printf("%d", big);
}

Upvotes: 4

MikeCAT
MikeCAT

Reputation: 75062

You have junk semicolon and big++ is executed regardless of c>='A' && c<='Z'.
You also have to initialize big.

Moreover, this code depends on the character code, so you should use isupper if it is not banned.

#include <stdio.h>
#include <ctype.h>

int main(int argc, char** argv) {
    int c;
    int big = 0;
    int small;
    while(c=getchar()){ /* this loop should go infinitely in most case : compare with EOF to detect the end of input */
        if(isupper(c))
            big++;
        printf("%d",big); /* maybe you want to print newline after this */
    }
    printf("end");
    return 0;
}

Upvotes: 5

ameyCU
ameyCU

Reputation: 16607

int big;

big is just declared not intialized , thus giving garbage value. 

int big=0;     // also initialize small

Would work.

And 

  if(c>='A' && c<='Z');
                      ^ will terminate if statement then and there

Due to ; big will be incrementated even if the if condition is false .Remove ; after if.

Upvotes: 4

Kamen Stoykov
Kamen Stoykov

Reputation: 1881

You have to initialize variable big with 0.

int big = 0;

Upvotes: 2

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