Basic database-like program in C using arrays - c

Question

I have just learnt about arrays. I was trying to create a database program using arrays. It's a very basic program.
#include<stdio.h>
#define N 1 //number of entries needed
int main()
{
int i, k = 1, l = 1, w, x = 0, y = 0;
int rollnum[N], hsc[N], cet[N], a[N], b[N];
char name[100], city[100], c;
for(i = 0; i < N; i++)
{
printf("%d.\n", (i+1));
printf("Enter first name : ");
do
{
c = getchar();
if(c != '\n')
{
name[k] = c;
k++;
}
}
while(c != '\n');
a[i] = k;
k++;
printf("\n");
printf("Enter roll number : ");
scanf("%d", &rollnum[i]);
printf("\n");
getchar();
printf("Enter city : ");
do
{
c = getchar();
if(c != '\n')
{
city[l] = c;
l++;
}
}
while(c != '\n');
b[i] = l;
l++;
printf("\n");
printf("Enter HSC percentage : ");
scanf("%d", &hsc[i]);
printf("\n");
printf("Enter CET marks : ");
scanf("%d", &cet[i]);
printf("\n");
getchar();
}
printf("\n\n\n");
k = 1;
l = 1;
for(i = 0; i < N; i++)
{
printf("Entry %d\n", (i+1));
printf("Student Name : ");
x = (a[i] - x);
for(w = 0; w < x; w++ && k++)
putchar(name[k]);
putchar('\n');
printf("Roll number : %d", rollnum[i]);
printf("\n");
printf("City : ");
y = (b[i] - y);
for(w = 0; w < y; w++ && l++)
putchar(city[l]);
putchar('\n');
printf("Marks : \n");
printf("\t");
printf("HSC : %d ", hsc[i]);
printf("\t");
printf("CET : %d / 200", cet[i]);
printf("\n\n\n");
}
return 0;
}
The program is not functioning the way I want it to! When I enter a name, the first letter is being printed out twice, same is the case with city! If I put 2 entries by modifying my 'N' , I'm getting the first letters of name and address(of second entry) as garbage values . I don't think there is any error in my logic, because i tried doing it manually in my notebook and I did not find any fault in it.
Can anyone help me find the mistake? I know the program might not at all be good and efficient, but I'm just trying out stuff that I've learnt!

Answer 1

You have made some mistakes initializing some variables. Also you don't have to read a string one character at a time. You can use scanf("%s", someString) to read a whole string.
And here is a working code that looks a lot more cleaner:
#include<stdio.h>
#define N 2
int main()
{
int rollnum[N], hsc[N], cet[N], i;
char name[100][100], city[100][100];
for(i = 0; i < N; i++)
{
printf("%d.\nEnter first name : ", (i+1));
scanf("%s", name[i]);
printf("\nEnter roll number : ");
scanf("%d", &rollnum[i]);
printf("\nEnter city : ");
scanf("%s", city[i]);
printf("\nEnter HSC percentage : ");
scanf("%d", &hsc[i]);
printf("\nEnter CET marks : ");
scanf("%d", &cet[i]);
printf("\n");
}
printf("\n\n\n");
for(i = 0; i < N; i++)
{
printf("Entry %d\nStudent Name : %s\nRoll number : %d\nCity : %s\nMarks : \n\tHSC : %d \tCET : %d / 200\n\n\n", (i+1), name[i], rollnum[i], city[i], hsc[i], cet[i]);
}
return 0;
}
It works for multiple entries too.
In order to make your program work you have to replace this:
x = (a[i] - x);
for(w = 0; w < x; w++ && k++)
putchar(name[k]);
putchar('\n');
printf("Roll number : %d", rollnum[i]);
printf("\n");
printf("City : ");
y = (b[i] - y);
for(w = 0; w < y; w++ && l++)
putchar(city[l]);
with this:
if (i == 0)
x = a[i]-1;
else
x = a[i] - a[i-1];
for(w = 0; w < x; w++)
putchar(name[k++]);
putchar('\n');
printf("Roll number : %d", rollnum[i]);
printf("\n");
printf("City : ");
if (i == 0)
y = b[i]-1;
else
y = b[i] - b[i-1];
for(w = 0; w < y; w++)
putchar(city[l++]);
the problem was that you didn't calculate the length of the words correctly, and also another error that I still can't explain but I removed that to.