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strcpy() in c gives me segmentation fault


strcpy() in c gives me segmentation fault

By : TOM
Date : September 24 2020, 04:00 AM
Hope this helps The pointer struct clients* first; doesn't point to any mallocd memory, so trying to access a property on it like first->client_id = 1 is an uninitialized pointer dereference.
Because behavior is undefined after the dereference, the segmentation fault could occur at strcpy (or anywhere else, but strcpy is not the culprit). Consider using a tool like valgrind to identify these illegal memory accesses when they occur.
code :
first->name = NULL;
memset(&first->name, 0, sizeof(first->name));
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct clients {
    int client_fd;
    char* name;
    struct clients* next;
};

int main(void) {
    struct clients* first = malloc(sizeof(*first));
    first->client_fd = 1;
    first->name = malloc(5);
    strcpy(first->name, "User");
    first->next = NULL;

    printf("%d %s\n", first->client_fd, first->name); // => 1 User

    free(first->name);
    free(first);
    return 0;
}


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strcpy() causes segmentation fault?

strcpy() causes segmentation fault?


By : user3560606
Date : March 29 2020, 07:55 AM
I hope this helps you . Whenever you have a string literal (in your case, "foo"), the program stores that value in a readonly section of memory.
strcpy wants to modify that value but it is readonly, hence the segmentation fault.
can't strcpy segmentation fault

can't strcpy segmentation fault


By : Bruce Long
Date : March 29 2020, 07:55 AM
I wish this help you You've got two syntax mistakes in your code. Your compiler must have warned you about them:
code :
sepwords[i] = malloc(3000);
Segmentation fault 11 on strcpy()

Segmentation fault 11 on strcpy()


By : bjornarg
Date : March 29 2020, 07:55 AM
this will help I keep getting a segmentation fault when I try to copy "init" into my string array, and I can't figure out why. If I comment out the strcpy() line, I don't get a segmentation fault and init prints fine. , You allocate an array of char *s:
code :
char **words =  malloc(sizeof(char*) * 2); 
strcat(*words,init);
strcat(words[0], init);
strcpy(*words, init);
*words = strdup(init);
words[0] = strdup(init);
Segmentation fault strcpy

Segmentation fault strcpy


By : Amit Sharma
Date : March 29 2020, 07:55 AM
it should still fix some issue , There are multiple problems in your code:
code :
#include <stdio.h>
#include <string.h>

typedef struct Movie {
    char hallName[50];
    char movieName[50];
} Movie;

...

void createHall(char *hallName) {
    Movie movie;
    snprintf(movie.hallName, sizeof movie.hallName, "%s", hallName);
    ...
    // do something with movie
}

void processCommand(char *line) {

    char *hallName = NULL;
    char *command = NULL;

    command = strtok(line, " ");

    if (command && strcmp(command, "CREATEHALL") == 0) {
        hallName = strtok(NULL, " ");
        if (hallName) {
            createHall(hallName);
        }
    }
}
Segmentation fault of strcpy()

Segmentation fault of strcpy()


By : Semjok M
Date : March 29 2020, 07:55 AM
I wish did fix the issue. If it worked, the code you wrote would print "World", not "WorldWorld". Nothing is appended, strcpy overwrites data only.
Your program crashes because "Hello" and "World" are string constants. It's undefined behavior to attempt to write to a constant, and in your case this manifests as a segmentation fault. You should use char x[] = "Hello"; and char y[] = "World"; instead, which reserve memory on the stack to hold the strings, where they can be overwritten.
code :
char foo[] = "foo";
strcpy(foo, "this string is waaaaaay too long");
return;
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