Scanf input for structs, bitfields in C

user_16689799 0
Viewed 204
#include <stdio.h>

typedef struct{
    unsigned int _1_:7;
    unsigned int _2_:7;
    unsigned int _3_:7;
    unsigned int _4_:7;
    unsigned int _5_:7;
} grades;

// ---other part of code---

grades student;
int main(){
    scanf("%u\n", student._1_)
    // all the others...
    return 0;
}

I don't know the way to do it. I tried to put & in front of student._1_ but it didn't work. If someone could show me how to do it, not only with bitfields but also with normal structs and enums.

c
4 Answers

Scanning to a temporary variable should help.

unsigned int tmp = 0;
scanf("%u\n", &tmp);
student._1_ = tmp;

BTW The error message should have informed you about the error reason.

user_67520500

Bitfields cannot have their address taken, and therefore you can't use scanf to write directly to them. You need to write to a temporary, then copy the value to the bitfield.

unsigned tmp;
scanf("%u", &tmp);
student._1_ = tmp;
user_16871190

final program I wrote, but now I have a ERROR with j & i variable in person.grades[1]

#include <stdio.h>


float average;
int i;
int j;

typedef struct{
    char* name_and_year[25];
    short grades[6];
} student;

student person;

void average_calculator(student *x){

    for(j = 0; j > 6; j++)
        average = (x->grades[0] + x->grades[1] + x->grades[2] + x->grades[3] + x->grades[4])/5.0;
    if(average >= 50){
        puts("You passed the year congratulations");
        x->grades[5] = 1;}
    else{
        puts("You didn't pass the year");
        x->grades[5] = 0;}
    printf("Your average is %.2f\n",average);
} 

void student_reader(){
    puts("Enter your full name & your year");
    scanf("%24[^\n]", person.name_and_year);
    puts("what were your grades?\n");
    for(i = 0; i > 6; i++)
        scanf("%hi", &(person.grades[i]));
}

int main(){

    student_reader();
    average_calculator(&person);

    return 0;
}
user_166897990

FINAL code for the readers, thx everybody

#include <stdio.h>

float average; short i;

typedef struct{
    char* name_and_year[25];
    short grades[6]; } student;

student person;

void average_calculator(student *x){

    for(i = 0; i < 5; i++){
        average += person.grades[i]/5;
    }
    if(average >= 50){
        puts("You passed the year congratulations");
        x->grades[5] = 1;}
    else{
        puts("You didn't pass the year");
        x->grades[5] = 0;}
    printf("Your average is %.2f\n",average); } 

void student_reader(){
    puts("Enter your full name & your year");
    scanf("%24[^\n]", person.name_and_year);
    puts("what were your grades?\n");
    for(i = 0; i < 5; i++){
        scanf("%hi", &(person.grades[i]));
    } }

int main(){

    student_reader();
    average_calculator(&person);
    return 0; }
user_166897990
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