The first test case passed but 2nd test case's output went to an infinite loop. And only evaluating before the # part of the string (2nd test case)

Question

Question:- Write a program that replaces the occurence of a given character (say c) in a primary string (say PS) with another string (say s).

Input: The first line contains the primary string (PS) The next line contains a character (c) The next line contains a string (s)

Output: Print the string PS with every occurence of c replaced by s.

NOTE: - There are no whitespaces in PS or s. - Maximum length of PS is 100. - Maximum length of s is 10.

Test Case-

1) Input:

abcxy
b
gh

Output:- aghxy

2) Input:

Al@bal#20owL
l
LL

Output:- ALL@baLL#20owL

This is the code I wrote:

#include<stdio.h>
#include<string.h>
int main()
{
char PS[105];
char Final[105];
char ch;
int i;
fgets(PS, sizeof(PS), stdin);
scanf("%c",&ch);
scanf("%s",Final);
for(i=0;i<strlen(PS);i++)
    {
    if(PS[i]==ch)
    {
    for(i=0;i<strlen(Final);i++)
    printf("%c",Final[i]);
    }
        else
    printf("%c",PS[i]);
    }


return 0;

}

I just edited it.. even with fgets , the error come is this In function main: test.c:10:2: error: too few arguments to function fgets fgets(PS); ^ In file included from test.c:1:0: /usr/include/stdio.h:622:14: note: declared here extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream) ^ — SrikantShrekk, Sep 05 '17 at 13:19
Hey Jean ... I tried with fgets too but I told in the above comment the error I get. — SrikantShrekk, Sep 05 '17 at 13:20
"I tried with fgets"-- [read the documentation](http://port70.net/~nsz/c/c11/n1570.html#7.21.7.2) for the [functions that you use](http://man7.org/linux/man-pages/man3/fgets.3.html); don't guess how they work. — ad absurdum, Sep 05 '17 at 13:32
i finally replaced gets(PS) with fgets(PS, sizeof(PS), stdin); . my first test case passed but in the 2nd test case it went on to a infinite loop "AL@baL@baL@baL@baL ...." and that too it is in loop considereing the strings before # .. I hope u got it.. — SrikantShrekk, Sep 05 '17 at 13:41
@Jean-FrançoisFabre : Why don't you wait on earth to sort the problem out by asker before voting it as a duplicate. There's always a second face to coin. Not all are same. — SrikantShrekk, Sep 05 '17 at 13:49
because it doesn't add anything useful to the site. Same questions and same answers (possibly good) all over again. — Jean-François Fabre, Sep 05 '17 at 13:50
@Jean-FrançoisFabre : I faced a new problem. I already posted. Can you help me out? — SrikantShrekk, Sep 05 '17 at 13:52
@SrikantShrekk-- don't modify your question when you have a new question; post a new question (and maybe search SO for duplicates first). — ad absurdum, Sep 05 '17 at 13:55
@DavidBowling : If I do that the first thing people will do it mark as duplicate. It's pity. There's an option to modify which will let users know what I did, and probably people won't mark me fake. — SrikantShrekk, Sep 05 '17 at 13:58
@dbush : I'm not pointing this at you but because of some non-patient people, after marking it duplicate crates the problem for the asker. Now, for the next 7 days I can't ask a new question just because they gave one advice and marked duplicate. I understand few guys are good at coding but doesn't mean in a minute you'll mark as duplicate. TRY TO UNDERSATND. I edited. sorted out. But now I cant post new question. Atleast give a breathe to the asker to think and edit. — SrikantShrekk, Sep 05 '17 at 14:03

score 2 · Accepted Answer · edited Sep 05 '17 at 13:31

The gets function is dangerous because it places no limit on the number of characters entered.

For example given the following code:

char str[10];
gets(str);

If the user were to enter a string 10 characters or longer, the result would be written off the end of the array. Doing so invokes undefined behavior.

A safer alternative is the fgets function which has the following signature:

char *fgets(char *s, int size, FILE *stream);

The first parameter is the buffer to receive the string, and the second is the size of that buffer. In your case you would call it like this:

fgets(PS, sizeof(PS), stdin);

Note that unlike gets, fgets will store a newline character in the resulting string if there is space for it.

Thank you @dbush @ TobySpeight .. Your above comment helped me for my first test case but in the 2nd test case it went on to a infinite loop "AL@baL@baL@baL@baL ...." and that too it is in loop considering the strings before # .. I hope u got it. — SrikantShrekk, Sep 05 '17 at 13:54

The first test case passed but 2nd test case's output went to an infinite loop. And only evaluating before the # part of the string (2nd test case)

1 Answers1