Understanding the goto Statement in C Programming

Syntax 1. Transfering the Control from top to down or below in the code

//code
goto label-name;
statement-1
statement-2
label-name:
statement-3
statement-4

Explanation:
The syntax of the goto statement can be broken down into two parts:
1.goto label_name;
2.label_name:

1. goto label_name; (Transfer Control)
The goto statement is used to jump to a specific part of the program marked by a label.
In the example above, when the program reaches the goto statement, it jumps directly to the line with the label label_name:. In this case, the label is placed below the goto, so the program skips over the lines in between and continues execution from the label onward.

Syntax 2. Transfering the Control from down to top

//code
label-name:
statement-1
statement-2
if(condition)
  goto label-name;
statement-3
statement-4

Explanation:
When the program reaches the goto statement, it immediately jumps to the label label-name:. In this example, the label is defined above the goto statement, so statement1 and statement2 will run normally until the condition in the if statement is true. If the condition is false, the program continues executing the rest of the code after the goto.

/* C program to check if a given number is even or using goto statement */
#include <stdio.h>
int main()
{
  int n ;
  printf("\n Enter Any Number");
  scanf("%d",&n);
  if (n % 2 == 0)
   /* transfer control to the label named even_n*/
   goto even_n;
  else
  // jump to label odd_n
  goto odd_n;
 even_n:
     printf("%d is even number", n);
  // return if even
  return;
 odd_n:
   printf("%d is odd number", n);
  return 0;
}
Output:
Enter Any Number
7
7 is odd number.

Explanation about the Program – Check Even or Odd Using goto in C.

This program in C enables us to check if a number is even or odd using a very simple goto statement. Although we do not usually recommend using goto for real-world coding, it is the best way by which learning how control jumps in a program becomes easy. Now, let's break it down stepwise.

Step 1: Start With a Number
int n;
pritnf("\n Enter Any Number");
scanf("%d", &n);
Before anything else, the program is supposed to ask the user to enter a number. That number will then be put into the variable n.
For example, if you enter 7, then n=7.

Step 2: Check Whether Even or Odd
if (n % 2 == 0)
  goto even_n;
else
   goto odd_n; This checks whether the given number is leaving a remainder.
If 0 is the remainder when the number divides by 2(n % 2 == 0), then the number is even and it will jump to even_n.
Otherwise goes odd_n.
Consider for example n = 7, 7 % 2 = 1, which is not equal to zero, thus it goes to odd_n.

Step 3: Print Result
If there is an even number:
even_n: printf("%d is even number", n); return;
It prints "4 is even number" if you entered 4 and then goes to end the program.

If there is an odd number:
odd_n: printf("%d is odd number", n);
It prints "7 is odd number" and continue further.

Example Result
Enter Any Number 7
7 is an odd number
Summary : This program gives a clear picture of jumping between labels in C using goto. Although modern programming hardly uses it, this example can help us understand how programs can be redirected on the base of some conditions.

/* C program to print numbers from 1 to 10 using goto statement */
#include <stdio.h>
int main()
{
 int n = 1;
 label:
   printf("%d ", n);
  n++;
   if (n <= 10)
   goto label;
  return 0;
}
Output:
1 2 3 4 5 6 7 8 9 10
Explanation:
We begin by setting n = 1. That’s the first number we want to show.

Then comes a label called label: — it’s just a spot in the code where we can jump back if needed. The program reaches this label and prints the current value of n. So at first, it prints 1.

Right after that, we increase n by 1. Now, n becomes 2.

Next, the program checks the condition if (n <= 10). This simply asks: Is the number still 10 or less?
If yes, the program jumps back to the label and repeats the same steps — printing the new value of n and increasing it again.

This process continues: 3, 4, 5... until n becomes 11.

At that point, the condition n <= 10 is no longer true. So, the program skips the goto and moves to the end, where it exits and stops running.