段故障，malloc char指针

Question

I keep getting a segmentation fault and i know its from the char pointer. But I cant figure out why?

Whiskey* createWhiskey(int a, double p, char* n){

    Whiskey* whiskey = malloc(sizeof(Whiskey));
    whiskey->age = a;
    whiskey->proof = p;
    whiskey->name = malloc((strlen(n)+1) * sizeof(char));
    strcpy(whiskey->name, n);
    return whiskey;
}
int main(){

    Whiskey* burbon;
    burbon = createWhiskey(12, 90.0, "MakersMark");

    free(burbon);

    return 0;
}

In a comment from Alex (see below) the following information is added:

typedef struct{ int age; double proof; char* name; }Whiskey;

Answer 1

As discussed in comments the program shown is fine.

However, you should add some checks to avoid problems. Something like:

typedef struct{ int age; double proof; char* name; } Whiskey;

Whiskey* createWhiskey(int a, double p, char* n){
    Whiskey* whiskey = malloc(sizeof(Whiskey));
    if (whiskey) 
    {
        whiskey->age = a;
        whiskey->proof = p;
        if (strlen(n) > SOME_MAXIMUM)
        {
            free(whiskey);
            printf("Some error... maybe\n");
            return NULL;
        }
        whiskey->name = malloc((strlen(n)+1) * sizeof(char));
        if (whiskey->name)
        {
            strcpy(whiskey->name, n);
        }
        else
        {
            free(whiskey);
            printf("Some error... \n");
            return NULL;
        }
    }
    return whiskey;
}

int main(){

    Whiskey* burbon;
    burbon = createWhiskey(12, 90.0, "MakersMark");
    if (!burbon)
    {
        printf("Some error... \n");
    }    

    // code....

    if (burbon)
    {
        free( burbon->name);
        free(burbon);
    }
    return 0;
}

Answer 2

I hope definition of your Whiskey structure is fine. Following code works fine for me:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct Whisk {
        int age;
        double proof;
        char *name;
} Whiskey;
Whiskey* createWhiskey(int a, double p, char* n){

    Whiskey* whiskey = malloc(sizeof(Whiskey));
    whiskey->age = a;
    whiskey->proof = p;
    whiskey->name = malloc((strlen(n)+1) * sizeof(char));
    strcpy(whiskey->name, n);
    return whiskey;
}

int main(){

    Whiskey* burbon;
    burbon = createWhiskey(12, 90.0, "MakersMark");
    if (!burbon)
    {
        printf("Some error... \n");
    }

    // code....

    if (burbon)
    {
        free( burbon->name);
        free(burbon);
    }
    return 0;
}

Answer 3

the following code

1. cleanly compiles
2. performs appropriate error checking
3. does not seg fault when run
4. performs the desired function
5. cleans up properly by passing both allocated memory pointers to free()
6. uses meaningful names for the passed parameters

the code:

#include <string.h>  // malloc()
#include <stdlib.h>  // exit(), EXIT_FAILURE
#include <stdio.h>   // perror()

typedef struct
{
    int age;
    double proof;
    char* name;
} Whiskey;

Whiskey* createWhiskey(int age, double proof, char* name)
{

    Whiskey* whiskey = NULL;
    if( NULL == (whiskey = malloc(sizeof(Whiskey)) ) )
    { // then, malloc failed
        perror( "malloc for Whiskey failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, malloc successful

    whiskey->age = age;
    whiskey->proof = proof;
    whiskey->name = NULL;

    if( NULL == (whiskey->name = malloc( strlen(name)+1) ) )
    { // then malloc failed
        perror( "malloc for name field failed" );
        free( whiskey );
        exit( EXIT_FAILURE );
    }

    // implied else, malloc successful

    strcpy(whiskey->name, name);
    return whiskey;
} // end function: createWhiskey


int main( void )
{

    Whiskey* burbon;
    burbon = createWhiskey(12, 90.0, "MakersMark");

    free( burbon->name );
    free( burbon );

    return 0;
} // end function: main