Consider the following three ANSI-C programs, P1, P2, and P3. Which one of the following statements is true? A) Only P1 will compile without any error B) Only P2 will compile without any error C) Only P3 will compile without any error D) All three programs P1, P2, and P3 will compile without any error

Official answer: A) Only P1 will compile without any error. Explanation: Let us analyze each program: 1. Program P1: - `int a = 5;` is declared at file (global) scope. - `int a = 7;` is declared inside the block scope of `main()`. - In ANSI-C, a local variable can shadow/hide a global variable with the same name. Hence, P1 compiles without any error. 2. Program P2: - Both `int a = 5;` and `int a = 7;` are declared within the same block scope of `main()`. - Redeclaring an identifier in the same scope is illegal and causes a compilation error (redefinition of variable `a`). 3. Program P3: - Both `int a = 5;` and `float a = 7;` are declared within the same block scope of `main()`. - Redeclaring an identifier with conflicting types in the same scope causes a compilation error. Thus, only P1 will compile without any error. Hence, option (A) is correct.

B) Only P2 will compile without any error

C) Only P3 will compile without any error

D) All three programs P1, P2, and P3 will compile without any error

Programming in C

GATE CSE 2026 Set 2 · Q19

MCQ1 markEasy

Time00:00

Consider the following three ANSI-C programs, P1, P2, and P3. Which one of the following statements is true?

Select one answerSingle correct

Pick an option to check

Solution

Step-by-step verified solution

Official answer: A) Only P1 will compile without any error

Programming in C

Let us analyze each program:

Program P1:
- int a = 5; is declared at file (global) scope.
- int a = 7; is declared inside the block scope of main().
- In ANSI-C, a local variable can shadow/hide a global variable with the same name. Hence, P1 compiles without any error.
Program P2:
- Both int a = 5; and int a = 7; are declared within the same block scope of main().
- Redeclaring an identifier in the same scope is illegal and causes a compilation error (redefinition of variable a).
Program P3:
- Both int a = 5; and float a = 7; are declared within the same block scope of main().
- Redeclaring an identifier with conflicting types in the same scope causes a compilation error.

Thus, only P1 will compile without any error. Hence, option (A) is correct.

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This Programming in C previous year question is Q19 of the GATE CSE 2026 Set 2 paper. Find more GATE CSE PYQs on Programming in C in Programming and Data Structures, or browse all GATE CSE PYQs.

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Programming in C in GATE CSE

Programming in C has 74 GATE CSE PYQs across 25 papers from 2011 to 2026. 20 of them are 1-mark MCQs like this one, and GATE CSE 2026 Set 2 has 3.

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.