Finding the error in my use of the strcat function

Question

Please help me i can't solve this question i've got in university. I asked in our university forum and they said this clue: "what is the difference if you send a long string to strcat, or you send the string B? "

Explain what is wrong with the next program:

#include <string.h>
#include <stdio.h>
int main()
{
    char A[10];
    char B[20];
    strcpy(A, "A student");
    strcpy(B, "fail the exam");
    printf("%s\n", strcat(A, B));
    return 0;
}

the program will output [ A student fail the exam ], can you be more clear with your question — Digital Alchemist, Jul 30 '13 at 05:53
Also note the missing space. Even if `A` is large enough, it would print `A studentfail the exam`. — ugoren, Jul 30 '13 at 07:18
Read: [`strcat()` implementation works but causes a core dump at the end](http://stackoverflow.com/users/1673391/grijesh-chauhan?tab=answers&sort=newest&page=5) — Grijesh Chauhan, Jul 30 '13 at 07:51
Welcome to SO. Should you find an answer acceptable, consider checking it. — chux - Reinstate Monica, Aug 09 '13 at 03:30

score 2 · Accepted Answer · answered Jul 30 '13 at 05:54

2

The first parameter of strcat must be large enough to contain the concatenated resulting string. So change it to :

char A[30];

or you will probably get a segmentation fault.

answered Jul 30 '13 at 05:54

Yu Hao

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score 2 · Answer 2 · answered Jul 30 '13 at 05:59

2

See "A student fail the exam" is large than 10.

So at least use char A[24] instead of char A[10]

answered Jul 30 '13 at 05:59

Lidong Guo

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Conor Taylor · Answer 3 · 2013-07-30T11:26:27.087

1

Because strcat(s,t) concatenates t to the end of s, s must be large enough to hold the new, concatenated string. It returns a pointer to the first character in s.

edited Jul 30 '13 at 11:26

answered Jul 30 '13 at 07:16

Conor Taylor

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score 0 · Answer 4 · answered Jul 30 '13 at 08:07

0

Array A should be large enough to hold the contents of array B other wise strcat behaviour is unpredictable, segmentation fault may occur, Application may get crash.Refer the link below. [Link]http://linux.die.net/man/3/strcat

answered Jul 30 '13 at 08:07

Raju

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Finding the error in my use of the strcat function

4 Answers4