strstr not returning desired result

Question

Can you identify the error in this code, it's not being able to print the song even though I pass the valid parameters to find

#include <stdio.h>
#include <string.h>

char tracks[][80] = {
    "I left my heart in Harvard Med School",
    "Newark, Newark - a wonderful town",
    "Dancing with a Dork",
    "From here to maternity",
    "The girl from Iwo Jima",
};

void find_track(char search_for[]) 
{
    int i;
    for(i = 0; i < 5; i++) {
        if (strstr(tracks[i], search_for)) {
            printf("Track %i: '%s'\n", i, tracks[i]);
        }
    }
}

int main() {
    char askedSong[80];
    printf("%s", "Hey buddy, what is the good one today? ");
    fgets(askedSong, sizeof(askedSong), stdin);
    find_track(askedSong);
    return 0;
}

Note that fgets() regards a newline as a valid char and loads it into the string. — Martin James, Apr 21 '21 at 17:50

score 2 · Answer 1 · answered Apr 21 '21 at 17:51

Suppose you can get "\n" at the end after fgets. Need to trim it (if you are inputing from the keyboard). You can try to run using file input: yourexefile.exe < input.txt > output.txt and find that it works somehow
Suppose you should break after finding the result in the cycle.

score 1 · Answer 2 · answered Apr 21 '21 at 17:55

The problem here is that fgets includes the trailing newline '\n' in askedSong.

Here's how I found it --- I ran the program in a debugger and put a breakpoint in find_track(). Then when prompted I put in "girl" on the command line and saw that the argument to the function is "girl\n".

Here's what I see in the debugger:

Hey buddy, what is the good one today? girl

Breakpoint 1, find_track (search_for=0x7fffffffd9c0 "girl\n") at test.c:15
15      for(i = 0; i < 5; i++) {
(gdb)

There's a lot of wacky ways to trim that '\n' in C: Removing trailing newline character from fgets() input

Thanks dude, the recommendation helped me! I didn't know about this thing of fgets inserting a new line character at the end at all. — Levi Ermonaites De Freitas, Apr 22 '21 at 15:32

score 1 · Answer 3 · answered Apr 21 '21 at 17:57

1

probleme with fgets extra \n (enter)

#include <stdio.h>
#include <string.h>

char tracks[][80] = {
    "I left my heart in Harvard Med School",
    "Newark, Newark - a wonderful town",
    "Dancing with a Dork",
    "From here to maternity",
    "The girl from Iwo Jima",
};

void find_track(char search_for[]) 
{
    int i;
    for(i = 0; i < 5; i++) {
        if (strstr(tracks[i], search_for)!=NULL) {
            printf("Track %i: '%s'\n", i, tracks[i]);
        }
    }
}

int main() {
    char askedSong[80];
    printf("%s", "Hey buddy, what is the good one today? ");
    scanf("%s",askedSong);// try to use scanf to ovoid \n in the buffer
    find_track(askedSong);
    return 0;
}

answered Apr 21 '21 at 17:57

fares

97
1
5

The problem is that scanf doesn't allow spaced strings, and furthermore, it has problem dealing with size as well. In my case I think it's not the best option. – Levi Ermonaites De Freitas Apr 22 '21 at 15:33
sorry for late response.but just for information you can allow spaced strings .and you can define the size of string example . ` scanf("%80[^\n]",askedSong);` .plz if you don't now it try it .it is very helpful . – fares Apr 26 '21 at 15:19

score 1 · Accepted Answer · answered Apr 21 '21 at 17:58

1

fgets leaves the newline in the string. Easy fix:

fgets(askedSong, sizeof(askedSong), stdin);
askedSong[strcspn(askedSong, "\n")] = 0;

answered Apr 21 '21 at 17:58

klutt

30,332
17
55
95

strstr not returning desired result

4 Answers4