C Variable Declaration and Scope (original) (raw)

Consider the following two C lines

C `

int var1; extern int var2;

`

Which of the following statements is correct

• Both statements only declare variables, don\'t define them.
• First statement declares and defines var1, but second statement only declares var2
• Both statements declare define variables var1 and var2

Predict the output

C `

#include <stdio.h> int var = 20; int main() { int var = var; printf("%d ", var); return 0; }

`

C `

#include <stdio.h> extern int var; int main() { var = 10; printf("%d ", var); return 0; }

`

• Compiler Error: var is not defined

C `

#include <stdio.h> extern int var = 0; int main() { var = 10; printf("%d ", var); return 0; }

`

• Compiler Error: var is not defined

Output?

C `

int main() { { int var = 10; } { printf("%d", var);
} return 0; }

`

Output?

C `

#include <stdio.h> int main() { int x = 1, y = 2, z = 3; printf(" x = %d, y = %d, z = %d \n", x, y, z); { int x = 10; float y = 20; printf(" x = %d, y = %f, z = %d \n", x, y, z); { int z = 100; printf(" x = %d, y = %f, z = %d \n", x, y, z); } } return 0; }

`

• x = 1, y = 2, z = 3
  x = 10, y = 20.000000, z = 3
  x = 1, y = 2, z = 100
• x = 1, y = 2, z = 3
  x = 10, y = 20.000000, z = 3
  x = 10, y = 20.000000, z = 100
• x = 1, y = 2, z = 3
  x = 1, y = 2, z = 3
  x = 1, y = 2, z = 3

C `

int main() { int x = 032; printf("%d", x); return 0; }

`

Consider the following C program, which variable has the longest scope?

C `

int a; int main() { int b; // .. // .. } int c;

`

Consider the following variable declarations and definitions in C

C `

i) int var_9 = 1; ii) int 9_var = 2; iii) int _ = 3;

`

Choose the correct statement w.r.t. above variables.

• Both i) and iii) are valid.
• Both i) and ii) are valid.

Find out the correct statement for the following program.

C `

#include "stdio.h"

int * gPtr;

int main() { int * lPtr = NULL;

if(gPtr == lPtr) { printf("Equal!"); } else { printf("Not Equal"); }

return 0; }

`

• It’ll always print Equal.
• It’ll always print Not Equal.
• Since gPtr isn’t initialized in the program, it’ll print sometimes Equal and at other times Not Equal.

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