I am a newbie with C and I am trying to run a program from my book which shows how we deal with arrays of structures.
#include<stdio.h>
#include<conio.h>
struct employee
{
int empno;
char name[30];
int basic;
int hra;
};
void main()
{
struct employee e[50];
int i, j, n;
int net[50];
float avg;
printf("Enter the number of employees: ");
scanf("%d", &n);
printf("Enter Emp. No. \tName:\tBasic\tHRA of each employee in the order.\n");
for(i=0; i<n; i++)
{
scanf("%d", &e[i].empno);
gets(e[i].name);
scanf("%d", &e[i].basic);
scanf("%d", &e[i].hra);
net[i]=e[i].basic + e[i].hra ;
avg = avg + net[i];
}
avg = avg/n;
printf("Emp. No \t Name-Netpay: ");
for(i=0; i<n; i++)
{
if(net[i]>avg)
{
printf("\t",e[i].empno);
printf("\t", e[i].name);
printf("\t", net[i]);
} } }
I also have further modules which goes on to compute the average and prints those elements whose salary + hr is more than average. However the code pasted above does not work as intended.
Now, if I enter the number of employees - Let's say 1, it only allows me to enter the empno and name and exits the loop. I am expecting it to complete at least one cycle through the loop with the value 1.
Any suggestions on this would be highly appreciated and I apologize if I am messing up anywhere. Thanks.
You need to flush the line from the input before using gets (which is deprecated btw):
#include <stdio.h>
struct employee
{
int empno;
char name[30];
int basic;
int hra;
};
int main()
{
struct employee e[50];
int i, j, n;
int net[50];
float avg;
printf("Enter the number of employees: ");
scanf("%d", &n);
printf("Enter Emp. No. \tName:\tBasic\tHRA of each employee in the order.\n");
for(i=0; i<n; i++)
{
scanf("%d", &e[i].empno);
char c;
while ((c = getchar()) != EOF && c != '\n');
gets(e[i].name);
scanf("%d", &e[i].basic);
scanf("%d", &e[i].hra);
net[i]=e[i].basic + e[i].hra ;
avg = avg + net[i];
}
return 0;
}
This is because scanf does not read the end of line (\n) but gets will and return immediately. scanf will read the name instead. Basically, it's a mess then :).
Related
I'm new to C. I've been tasked to run a program that calculates the percentage of students that passed an exam,based on N grade inputs.I don't really understand how functions work in though.This is what I came up with
#include <stdio.h>
#define MAX_N 300
main()
{
int N,grade,i;
float success(N)
{
float sum=0.0;
for (i=0;i<N;i++) {
if (grade>=5) {
sum+=1;
}
float success=sum/N;
return(success);
}
}
printf("How many students? ");
scanf("%d",&N);
printf("Enter grades(0-10) of %d students ",N);
for (i=0;i<N;i++){
scanf("%d",&grade);
}
printf("%f percent of students have passed the exam ",success(N);
return(0);
}
It looks like it should work, however I always get the wrong result.It is stuck on displaying 0.2 or 0.25 for any input I give.Can somebody help?
The problem is that in grade only the last entered data is being stored. Make grade as an array so that all data can be stored.
I guess you are taking multiple value for grade and not taking array for it.
grade should be an array and in loop scanf("%d",&grade[i]); should be implement.
grade should be an array of N integers so that each and every value is stored. You also forgot to multiply success by 100 to get the percentage.
I think I fixed the code:
#include <stdio.h>
#define MAX_N 300
float success(int grade[],int N)
{int i;
float sum=0.0;
for (i=0;i<N;i++) {
if (grade[i]>=5) {
sum+=1;
}
}
float success=sum/N;
return(success*100);
}
int main(){
int N, i;
printf("How many students? ");
scanf("%d",&N);
int grade[N];
printf("Enter grades(0-10) of %d students ",N);
for(i=0;i<N;i++){
scanf("%d", &grade[i]);
}
printf("%f percent of students have passed the exam ", success(grade, N));
return(0);
}
I think you should examine the code I wrote. A little bad code. But it can help.
#include <stdio.h>
int students_success(int *);
int main() {
int n;
printf("How many students?\n");
scanf("%d", &n);
printf("Enter grades(0-10) of %d students\n", n);
int grade;
int pass_std = 0;
for(int i = 0; i < n; ++i) {
scanf("%d", &grade);
pass_std = students_success(&grade);
}
printf("%.2f percent of students have passed exam.\n", (double)pass_std / n);
}
int students_success(int *grade) {
static int pass_std = 0;
if(4 < *grade) {
++pass_std;
}
return pass_std;
}
I am new to C and I've run into a bit of a problem when it comes to user input for an array.
Here is the code
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int n, i;
int score [n];
printf("Number of scores: ");
scanf("%d", &n);
for(i=0; i<n; i++){
printf("score: ");
scanf("%d", &score[i]);
}
return 0;
}
It does not matter what value I set for n. It always prompts the user 4 times.
As mentioned in comments, you must change this:
/* bad */
int score [n];
printf("Number of scores: ");
scanf("%d", &n);
into this
/* good */
printf("Number of scores: ");
scanf("%d", &n);
int score [n];
This since C executes code from top to bottom like when you are reading a book. It will not "double back" a few rows above and fill in n once it has been entered by the user. At the point where you declare int score [n], n must already be known.
If your using an array with unknown size during compilation, I would suggest using memory allocation. So the user determines the array size while running the program.
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int n, i;
int *score;
printf("Number of scores: ");
scanf("%d", &n);
score = (int *)malloc(sizeof(int)*n);
for(i=0; i<n; i++){
printf("score: ");
scanf("%d", &score[i]);
}
free(score)
return 0;
}
The malloc function allocates memory with the size of n and returns a pointer to the allocated memory.
I have a school project which asks me to write a code using struct and functions, regarding sales in Greek cities. You are prompted to enter the values of 'em. The program works just fine if I enter that there's 6 salesmen, but a number larger than that makes it stop after entering all the values.. An example would be:
Number of salesmen: 7
(
Enter the his id:
Enter his surname:
Enter the number of sales:
Enter the area code:
) x7 times.
Then, when you enter the last value, it would just stop. Not exit, not stop responding/crash, literally just stop, and you would be unable to type anything more, only option would be to exit.
Thing is, there's no error or warning in both the build messages and the log, which has me quite confused.
My guess is that the error is in the function "calcSales" but I wanted to post the whole code just in case you need more info on it.
Could you take a look at the code and tell me if you find anything wrong? Thank you.
#include <stdio.h>
#include "genlib.h"
#include <simpio.h>
#include <string.h>
#define N 20
#define M 4
struct{
int id;
char surname[16];
long sales;
int area;
} salesmen[N];
void info(int *count);
void calcSales(int *count);
int main(){
int count;
printf("Give me the number of salesmen:\n");
count=GetInteger();
info(&count);
calcSales(&count);
}
void info(int *count){
for (int i=0; i<*count; i++){
printf("\nInfo for salesman number %d:\n", i+1);
printf("\nGive me his id: ");
salesmen[i].id=GetInteger();
printf("\nGive me his surname: ");
gets(salesmen[i].surname);
printf("\nGive me the number of sales: ");
salesmen[i].sales=GetLong();
printf("\n 1=Thessaloniki, 2= Athens, 3= Volos, 4= Hrakleio \n");
printf("\nLastly, give me the number of his area: ");
salesmen[i].area=GetInteger();
if (salesmen[i].area>4){
printf("\nThe number you are trying to enter doesn't match to an area.\n");
break;
}
}
}
void calcSales(int *count){
long tSales[4];
for (int i=0; i<*count; i++){
tSales[i]=0;
}
for (int i=0; i<*count; i++){
if(salesmen[i].area==1){
tSales[0]+=salesmen[i].sales;
}
if(salesmen[i].area==2){
tSales[1]+=salesmen[i].sales;
}
if(salesmen[i].area==3){
tSales[2]+=salesmen[i].sales;
}
if(salesmen[i].area==4){
tSales[3]+=salesmen[i].sales;
}
}
for (int i=0; i<4; i++){
printf("\nSales for area number %d: %ld\n",i+1, tSales[i]);
}
}
Your guess is correct. The mistake in calcSales function.
Exactly, the following part:
long tSales[4];
for (int i=0; i<*count; i++) {
tSales[i]=0;
}
The *count has value of 20. Which means the loop goes from i = 0 until i = 19.
When you access tSales[i] for i = 4 and above. You're invoking an undefined behavior. It's a memory that you didn't reserve for tSales. I suggest using the following:
long tSales[4];
for (int i=0; i<4; i++) {
tSales[i]=0;
}
Or better:
long tSales[4];
for (int i=0; i<sizeof(tSales)/sizeof(tSales[0]); i++) { // number of elements is the total size of array divided by the size of one element.
tSales[i]=0;
}
Or even better, you don't need a loop at all:
long tSales[4] = {0};
Besides your problem:
For the code you're providing, you don't need to pass a pointer to the functions.
You can make the code look as follows:
#include <stdio.h>
#include "genlib.h"
#include <simpio.h>
#include <string.h>
#define N 20
#define M 4
struct{
int id;
char surname[16];
long sales;
int area;
} salesmen[N];
void info(int count);
void calcSales(int count);
int main(){
printf("Give me the number of salesmen:\n");
int count=GetInteger(); // I've made declaration and assignment in same line. That seems cleaner to me.
info(count);
calcSales(count);
}
void info(int count){
for (int i=0; i<count; i++){
printf("\nInfo for salesman number %d:\n", i+1);
printf("\nGive me his id: ");
salesmen[i].id=GetInteger();
printf("\nGive me his surname: ");
gets(salesmen[i].surname);
printf("\nGive me the number of sales: ");
salesmen[i].sales=GetLong();
printf("\n 1=Thessaloniki, 2= Athens, 3= Volos, 4= Hrakleio \n");
printf("\nLastly, give me the number of his area: ");
salesmen[i].area=GetInteger();
if (salesmen[i].area>4 || salesmen[i].area < 1){ // Added an extra condition.
printf("\nThe number you are trying to enter doesn't match to an area.\n");
break;
}
}
}
void calcSales(int count){
long tSales[4] = {0};
for (int i=0; i<count; i++){
tSales[salesmen[i].area - 1]+=salesmen[i].sales; // No need for if conditions.
}
for (int i=0; i<4; i++){
printf("\nSales for area number %d: %ld\n",i+1, tSales[i]);
}
}
Hi I have to create a database that stores students number, name and also stores an array of course marks (1-N) in C Programming Language.
Everything worked until I started coding for the array of course marks. Then every time I compiled the code it kept crashing as soon as it asked to input the course marks.
Can you please tell me where I'm going wrong in my programming for this task? I have attached it to this message.
The program worked for inputting the name, student number, however I could not get the program to input array of marks. I have asked how many course marks to be entered and then used a for loop within the "void insert(void)" function to keep inputting the course marks into the array *marks. I am referring specifically to lines 24 to 30 in my programming code.
Always at this point the program kept crashing and I could not proceed further to enter more names or print the stored student details.
I think there is a problem with this part:
for (i= 0; i < num_marks; i++)
{
printf("Enter Course Mark: \n");
scanf("%d", &(list[num_students].marks[num_marks]));
}
Anyway here is the full code:
#include <stdio.h>
#include <string.h>
struct student{
int number;
char name[10];
int marks[5];
};
struct student list[10];
int num_students = 0;
int num_marks = 0;
int *p;
void insert(void)
{
int student_number;
int i;
printf("Enter number: \n");
scanf("%d", &list[num_students].number);
printf("Enter NAME: \n");
scanf("%s", &list[num_students].name);
printf("Enter NO of courses: \n");
scanf("%d", num_marks);
for (i= 0; i < num_marks; i++)
{
printf("Enter Course Mark: \n" );
scanf("%d", &(list[num_students].marks[num_marks]));
}
num_students++; // HOW DO WE INPUT ARRAY MARKS??? MARK1: , MARK2: , MARK3 ,
}
void printtest(void)
{
int i;
for (i=0; i < num_students; i++)
{
printf("Name: \n");
puts(list[i].name);
printf("Number: %d \n", list[i].number);
printf("Mark: %d /100 \n", list[i].marks);
printf("\n");
}
}
int main(void)
{
int code;
int opt1;
int courses, i, k, j, counter;
for (;;){
printf("Enter operation code: \n");
printf("(1) ADD NEW STUDENT DETAILS: \n");
printf("(2) DISPLAY REPORT OF ALL STUDENTS: \n");
scanf(" %d", &code);
switch (code){
case 1 :
insert();
break;
case 2 :
printtest();
break;
default:
printf("Illegal code\n");
printf("\n");
}
}
}
Apart from what others pointed out, I'd like to draw your attention towards the following:
void insert(void)
{
int student_number;
int i;
printf("Enter number: \n");
scanf("%d", &list[num_students].number);
printf("Enter NAME: \n");
scanf("%s", &list[num_students].name);
printf("Enter NO of courses: \n");
scanf("%d", num_marks);
for (i= 0; i < num_marks; i++)
{
printf("Enter Course Mark: \n" );
scanf("%d", &(list[num_students].marks[num_marks]));
}
num_students++;
}
void printtest(void)
{
int i;
for (i=0; i < num_students; i++)
{
printf("Name: \n");
puts(list[i].name);
printf("Number: %d \n", list[i].number);
printf("Mark: %d /100 \n", list[i].marks);
printf("\n");
}
}
There are three problematic statements:
scanf("%s", &list[num_students].name); This is why beginners should use compilers with all warnings enabled.
printf("Mark: %d /100 \n", list[i].marks); What did you declare marks as in the first place?
scanf("%d", num_marks); Seems like you put & operator where not needed and ignore where needed. Read your textbook before asking a question next time.
Seems like you're having a tough time understanding the concept of arrays and pointers. Read your text book thoroughly before venturing into the world of pointers. If you don't use them correctly, even compiler can't help you.
Also, even if I don't expect your program to have a robust input mechanism, at least array bounds checking is expected. Learn good habits from the beginning. They'll save a lot of your time while debugging later.
Seems to be an error in:
for (i= 0; i < num_marks; i++)
{
printf("Enter Course Mark: \n" );
scanf("%d", &(list[num_students].marks[num_marks]));
}
The crash is probably because num_marks as index indexes beyond the array. Change to:
for (i= 0; i < num_marks; i++)
{
printf("Enter Course Mark: \n" );
scanf("%d", &(list[num_students].marks[i]));
}
I need help on two questions, Its not homework but its to study for an exam. I need to have these questions because i was allowed 1 full page of notes for the exam. If you could help me these two simple questions for me that would be great. Here are the questions:
"Write a function called getGrades. The function that repeatedly prompts the user for positive integers until the user enters a negative value to stop. The function should return the average of these grades and the highest grade."
"Write a function called Get_Info that takes a pointer to a student structure, (that has three fields: char array called name, an int id, and a double gpa) as its only argument. The function prompts the user for the required information to fill the structure and stores it in the appropriate fields."
What I have so far, Let me know if they are correct and if i need to add anything.
1.
double getGrades() {
double average;
double i;
For(i=1 ; i<i; i++)
{
printf("Enter Grade1:\n");
scanf("%lf", &i);
}
if (i<0)
{
(double) average == (grade1 + grade2 + grade3) / 3;
return average;
}
}
2.
typedef struct {
int id;
double gpa;
char name[SIZE];
} student;
void Get_Info(student list[], int num) {
int i;
for(i=0; i<num; i++) {
printf("\nName:%s", list[i].name);
printf("\nGPA:%lf", list[i].gpa);
printf("\nID: %d\n", list[i].id);
}
}
On #1: The requirement is that the function accept ints. You are scanning for doubles.
The requirement is "The function should return the average of these grades and the highest grade." You only return one double, when two different outputs are called for.
Your for loop is written as "For" (C is case-sensitive), and is based on the test i<i. When will i ever be less than itself??
Here's my version of it.
double getGrades(int* max)
{
int sum = 0;
int input;
int i = 0;
*max = 0;
printf("Enter Grade #%d:\n", i+1);
scanf("%d", &input);
while (input > 0) {
if (*max < input) {
*max = input;
}
sum = sum + input;
i++;
printf("Enter Grade #%d:\n", i+1);
scanf("%d", &input);
}
return i? ((double)sum / i) : 0;
}
Your #2 is much better than your #1, but still has some errors:
The requirement is that the function takes a pointer to a student struct, NOT an array.
It should then print a series of Prompts, and get a series of answers (just as you did in #1).
This is a sequence of printf/scanf.
And when using scanf, you typically pass the ADDRESS of the variable, using &.
(strings are a exception, however)
Here is my version:
typedef struct {
char name[SIZE];
int id;
double gpa;
} student;
void Get_Info(student* ps) {
printf("Enter Name\n");
scanf("%s", ps->name);
printf("Enter ID:\n");
scanf("%d", &ps->id);
printf("Enter GPA\n");
scanf("%lf", &ps->gpa);
}
Try this. It should seem intuitive enough:
double getGrades() {
double average;
double grade;
double total = 0;
int count = 0;
while (1) {
printf("Enter grade: ");
scanf("%d", &grade);
if (grade < 0) {
if (count == 0) {
average = 0;
break;
}
average = total/count;
break;
}
count++;
total += grade;
}
return average;
}