This program should ask you to add member (people) to a struct and print them on a file but after the first for loop just stop working and jump over the name part. I just found that thing that allow you to add space to a string, tried it but no success... I tried to remove it and it work without any problem so the [^\n] make something go wrong. What is wrong ?

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

struct Staff {
    char Surname[100];
    char Name[100];
    int age;
    char spec[100];
    int id;
} person;

void write();
void leggi();
void trova();

int main() {
    write();
}

void write() {
    int i = 0;
    int n = 1;
    int r;

    FILE *fp;
    fopen_s(&fp, "index.txt", "w ");
    if (fp == NULL) {
        printf("Failed to open file\n");         
        exit(1);
    }

    fprintf(fp, "%d\n", i);

    for (i = 0; i < n; i  ) {
        printf("Surame:\n");
        scanf_s("%[^\n]s", person.Surname, 100);
        fprintf(fp, "%s\t\t", person.Surname);
                                             //loop just get over the name part 
        printf("Name:\n");                   //after the first loop
        scanf_s("%s", person.Name, 100);               
        fprintf(fp, "%s\t", person.Name);

        printf("Age:\n");                  
        scanf_s("%d", &person.age);
        fprintf(fp, "%d\t", person.age);

        printf("Specialization\n");
        scanf_s("%s", person.spec, 100);
        fprintf(fp, "%s\n", person.spec);

        printf("Want to enter another? 1=yes  0=no...\n");
        scanf_s("%d", &r);
        if (r == 1)
            n = n   1;
    }

    rewind(fp);
    fprintf(fp, "%d\n", i);    

    fclose(fp);
}

CodePudding user response：

There are multiple problems in your code:

• you use the so called secure functions fopen_s, scanf_s etc, but you do not check the return values to detect invalid input. You should instead use standard functions, pass the appropriate arguments and check the return values.

• using scanf_s is actually non portable: the scanf_s function defined in Annex K of the C Standard requires the length argument after the pointer to have size_t type, whereas the function with the same name in the Microsoft library uses type UINT, which has a different representation on 64-bit versions of their Windows OS. A classical case of the Embrace, enhance and extinguish strategy. In Standard C, one should write: scanf_s("%s", person.Name, (size_t)100) or better:

  scanf_s("%s", person.Name, sizeof person.Name)

• there is no need to open the output file for update with "w ", just use "w".

• you rewind the stream pointer back to the beginning of file and overwrite the number of entries at the start of the file. This works as long as you have less than 10 entries, but beyond that, the number has more digits so some characters in the file will be corrupted. You could use a format with padding such as "m\n" which would allow for up to 1 million records without risks.

• "%[^\n]s" is not a correct scanf format: you should just write "%[^\n]" or better "