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- Question
Macro calls and function calls work exactly similarly.
Options- A. True
- B. False
- Correct Answer
- False
ExplanationFalse, A macro just replaces each occurrence with the code assigned to it. e.g. SQUARE(3) with ((3)*(3)) in the program.A function is compiled once and can be called from anywhere that has visibility to the funciton.
C Preprocessor problems
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- 1. Preprocessor directive #ifdef .. #else ... #endif is used for conditional compilation.
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, these macros are used for conditional operation.- 2. A preprocessor directive is a message from programmer to the preprocessor.
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, the programmer tells the compiler to include the preprocessor when compiling.- 3. The preprocessor can trap simple errors like missing declarations, nested comments or mismatch of braces.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
False, the preprocessor cannot trap the errors, it only replaces the macro with the given expression. But the compiler will detect errors.- 4. What will be the output of the program?
#include<stdio.h> #define MAX(a, b, c) (a>b? a>c? a : c: b>c? b : c) int main() { int x; x = MAX(3+2, 2+7, 3+7); printf("%d\n", x); return 0; }
Options- A. 5
- B. 9
- C. 10
- D. 3+7 Discuss
Correct Answer: 10
Explanation:
The macro MAX(a, b, c) (a>b ? a>c ? a : c: b>c ? b : c) returns the biggest of given three numbers.Step 1: int x; The variable x is declared as an integer type.
Step 2: x = MAX(3+2, 2+7, 3+7); becomes,
=> x = (3+2 >2+7 ? 3+2 > 3+7 ? 3+2 : 3+7: 2+7 > 3+7 ? 2+7 : 3+7)
=> x = (5 >9 ? (5 > 10 ? 5 : 10): (9 > 10 ? 9 : 10) )
=> x = (5 >9 ? (10): (10) )
=> x = 10
Step 3: printf("%d\n", x); It prints the value of 'x'.
Hence the output of the program is "10".
- 5. What will be the output of the program?
#include<stdio.h> #define MAN(x, y) ((x)>(y))? (x):(y); int main() { int i=10, j=5, k=0; k = MAN(++i, j++); printf("%d, %d, %d\n", i, j, k); return 0; }
Options- A. 12, 6, 12
- B. 11, 5, 11
- C. 11, 5, Garbage
- D. 12, 6, Garbage Discuss
Correct Answer: 12, 6, 12
Explanation:
The macro MAN(x, y) ((x)>(y)) ? (x):(y); returns the biggest number of given two numbers.Step 1: int i=10, j=5, k=0; The variable i, j, k are declared as an integer type and initialized to value 10, 5, 0 respectively.
Step 2: k = MAN(++i, j++); becomes,
=> k = ((++i)>(j++)) ? (++i):(j++);
=> k = ((11)>(5)) ? (12):(6);
=> k = 12
Step 3: printf("%d, %d, %d\n", i, j, k); It prints the variable i, j, k.
In the above macro step 2 the variable i value is increemented by 2 and variable j value is increemented by 1.
Hence the output of the program is 12, 6, 12
- 6. If the file to be included doesn't exist, the preprocessor flashes an error message.
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, the included file does not exist it will generate the error.- 7. Preprocessor directive #undef can be used only on a macro that has been #define earlier
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, #undef can be used only on a macro that has been #define earlierExample: #define PI 3.14
We can undefine PI macro by #undef PI
- 8. Once preprocessing is over and the program is sent for the compilation the macros are removed from the expanded source code.
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, After preprocessing all the macro in the program are removed.- 9. Every C program will contain at least one preprocessor directive.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
False, the preprocessor directive is not mandatory in any c program.- 10. A header file contains macros, structure declaration and function prototypes.
Options- A. True
- B. False Discuss
Correct Answer: True
Explanation:
True, the header file contains classes, function prototypes, structure declaration, macros.
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