CODEWITHSUNDEEP
c
Yamaha32088
Yamaha32088

Reputation: 4163

How to make sure user inputs a value?

I am trying to get this code to verify that the user input a value. It works if i use gets() but when I change it to fgets() it stops working. I want it to keep looping until the user enters a string of at least 1 character but less than 25 I am new to programming if it isn't apparent in my code. Thanks!

int main(void)
{
    char input[25], inputNew[25];
    int i;
    int x;
    int y;
    do
    {
        printf("Please enter a string less then 25 characters!\n");
        fgets(input, sizeof(input), stdin);  
        y = strlen(input);  
    }
    while(y>25 || y<=0);

    for (i = 0; i <= strlen(input); i++)
    {
        inputNew[i] = toupper(input[i]);
        for (x = 1; x <= strlen(input); x+=2)
        {
        inputNew[x] = tolower(input[x]);
        }
    }
    printf("The new value is: %s.\n", inputNew);
return 0;
}

Upvotes: 2

Views: 187

Answers (4)

Antarus
Antarus

Reputation: 1621

you have declared the variable input with a static size 25 . So i don't see a chance of it getting a larger size for y = strlen(input);

Change your 

char input[25];

to 

char input[100];

anything more than 25.

Upvotes: 0

Mario The Spoon
Mario The Spoon

Reputation: 4869

nneonneo beat me to the answer:

The gets() function is equivalent to fgets() with an infinite size and a stream of stdin, except that the newline character (if any) is not stored in the string.

From http://www.manpagez.com/man/3/fgets/

I just added the references...

Upvotes: 0

alecov
alecov

Reputation: 5171

First of all, avoid gets() in any serious code. gets() is ill-designed and not safe. Never use it.

Second. fgets() keeps the newline at the end of the buffer (while gets() discards it).

Third, y <= 0 is probably wrong in the case of fgets(), since it will likely read at least one character (the newline). You should replace it with y < 2.

Last, and most important: please indent your code. :)

Upvotes: 1

nneonneo
nneonneo

Reputation: 179552

fgets keeps the ending newline, whereas gets throws it out.

Therefore, you'll have to change your check to y <= 1 if you use fgets.

Upvotes: 6

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