A. Odd Loop (Definition)

An odd loop is a loop in which the number of iterations (repetitions) is not known in advance and depends on some condition evaluated during runtime.

• In an odd loop, the user or some event decides when the loop should stop.
• The exact number of times the loop body executes is unpredictable at compile time.
• Example situations: Reading input until user says "no", processing data until end-of-file is reached.

Common implementation:

char ch = 'y';
while(ch == 'y')
{
    printf("Enter data: ");
    // process data
    printf("Continue? (y/n): ");
    scanf(" %c", &ch);
}

Here, the loop runs an odd (unknown) number of times depending on user input.

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B. Goto and Label (Definition)

goto is an unconditional branching statement in C that transfers the control of the program to a specified label without checking any condition.

A label is a user-defined identifier followed by a colon (:) that marks a position in the program where control can be transferred using goto.

Syntax:

goto label_name;
// ...
label_name:
    statement;

Key Points:

• goto causes an unconditional jump to the labeled statement.
• The label must be in the same function as the goto statement.
• Excessive use of goto makes code difficult to read and debug (spaghetti code), so it is generally avoided in structured programming.

Example:

printf("Hello\n");
goto skip;
printf("This will be skipped\n");
skip:
printf("World\n");

Output: Hello → World (middle statement is skipped)

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C. Program to Generate the Pattern

Pattern:

1
2 2
3 3 3
4 4 4 4

Program in C:

#include <stdio.h>

int main()
{
    int i, j;

    for(i = 1; i <= 4; i++)
    {
        for(j = 1; j <= i; j++)
        {
            printf("%d ", i);
        }
        printf("\n");
    }

    return 0;
}

Explanation:

• The outer loop (i) runs from 1 to 4, representing each row.
• The inner loop (j) runs from 1 to i, printing the value of i repeatedly.
• After the inner loop completes, \n moves the cursor to the next line.

Dry Run:

• When i = 1 → inner loop runs 1 time → prints: 1
• When i = 2 → inner loop runs 2 times → prints: 2 2
• When i = 3 → inner loop runs 3 times → prints: 3 3 3
• When i = 4 → inner loop runs 4 times → prints: 4 4 4 4

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Conclusion: Odd loops are useful when iteration count is runtime-dependent, goto provides unconditional branching to a label, and nested for loops are the standard approach for generating number patterns.