Array and Loops

[MAhmed]

Having problem it says "mark is undefined.
line #9

  #include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
for(int a=0;a<3;a++)
{
 printf("Subject %d:"); scanf("%d", &mark[a]);
 int tot=mark[1]+mark[2]+mark[3];
 printf("%d",tot); }
 getch();
 }

[shadder]

Hi,

could you explain this?

printf("Subject %d:");

[MAhmed]

printf("Subject %d:",a);
corrected it
still same error that mark is undefined

[shadder]

remove the , (comma operator) and try

[MAhmed]

still the same error

[Nico]

Probably that is because you try to use a variable called mark at line 9 and 10:

scanf("%d", &mark[a]);
int tot=mark[1]+mark[2]+mark[3];

But you don't create a variable called mark before you try to use it, so for the compiler the variable mark is indeed undefined.
You should either remove these lines or create an array of integers called mark somewhere before line 7.

[MAhmed]

how to create it?

[shadder]

You haven't declared mark[], you have to declare it first to use it

[MAhmed]

please correct the code someone
i want to take output from user
for example
subject 1: 78 etc
and add them all and give output its sum.
using array and loops

[shadder]

Warning I haven't learnt C yet, so there may be some errors which I can't see

 #include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
int mark[3],b=0,tot=0;
for(int a=0;a<3;a++)
{b=a+1;//for index

 printf("Subject %d:",&b);
 scanf("%d", &mark[a]);
 tot+=mark[a];

}


 printf("%d",tot); }
 getch();
 }

HOPE IT HELPS :)

[sadij97]

I don't know C but in C++ you can use dynamic arrays with runtime size to do something like this. run it on cpp.sh

#include<iostream>

int main()
{
    int sum=0;
    int ENTRY;
    std::cout<<"Enter how many numbers you want to add: " ;
    std::cin>>ENTRY;
    int *input= new int[ENTRY];
    for(int i=0; i<ENTRY; ++i)
    {
        std::cout<<"Enter entry no. "<<i+1<<"\n";
        std::cin>>input[i];
        sum+=input[i];
    }
    std::cout<<"Sum = "<<sum<<"\n";
    delete[] input;

}