C program core dumped when writing to a file

Question

I am new to C program and I am working on a program which is writing a set of struct to a .txt file.

This is my try:

#include <stdio.h>

struct FileSig {
    char name[256];  
    char mode;   
    char user_id;   
    char group_id;   
    char size;  
    char time_last_mod[50]; 
};


int main(int argc, char **argv)
{
    struct FileSig FileSig1;
    FILE *fp_Out;
    fp_Out = fopen( "out.txt" , "w" );

    printf("Enter name: ");
    scanf("%s", FileSig1.name);
    fprintf(fp_Out, "Name: %s\n", FileSig1.name);

    printf("Enter mode: ");
    scanf("%s", FileSig1.mode);
    fprintf(fp_Out, "Mode: %s\n", FileSig1.mode); 

    printf("Enter user id: ");
    scanf("%s", FileSig1.user_id);
    fprintf(fp_Out, "userID: %s\n", FileSig1.user_id); 

    printf("Enter group id: ");
    scanf("%s", FileSig1.group_id); 
    fprintf(fp_Out, "groupID: %s\n", FileSig1.group_id); 

    printf("Enter size: ");
    scanf("%s", FileSig1.size);
    fprintf(fp_Out, "size: %s\n", FileSig1.size);  

    printf("Enter time last modifly: ");
    scanf("%s", FileSig1.time_last_mod);
    fprintf(fp_Out, "time_last_mod: %s\n", FileSig1.time_last_mod);  

//  fp_Out = fopen( "out.txt" , "w" );
//  fprintf(fp_Out, "Name: %s\nMode: %d\nUserID:%d\nGroupID: %d\nSize:%d\nTime last modifly:%s", FileSig1.name, FileSig1.mode, FileSig1.user_id, FileSig1.group_id, FileSig1.size, FileSig1.time_last_mod);

    fclose(fp_Out);

    return 0;
}

When I run it after the second input it said Segmentation fault (core dumped).

More anyone please help me with this? I am new on this and I am like to learn.

Answer 1

The "%s" format specifier is for strings. But mode is a character. Use "%c" for characters. Also, pass the address you want the character stored in to scanf , not an uninitialized value.

Answer 2

"%s" is for strings, but mode is of type char , thus you should use "%c", like this:

scanf("%c", &FileSig1.mode);
fprintf(fp_Out, "Mode: %c\n", FileSig1.mode); 

Notice how I took the address of mode , since scanf() takes a pointer as an argument.

PS: You need to change all your scanf and printf that read a character instead of a string to follow this advice.