constants Questions and Answers

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Constants are one of the most fundamental topics in C programming. This set of constants in C language questions with answers covers the use and declaration of constants, symbolic names, and constant data types. For students preparing for GATE, Infosys, or Tech Mahindra placement exams, understanding constants helps you write more reliable and readable code. These C programming MCQs are designed to strengthen your basics in data storage, syntax, and memory management. Each question includes clear explanations to help you differentiate between literals, symbolic constants, and macros effectively.

constants

Showing 10 of 30 questions

1. What will be the output of the program? #include<stdio.h> int main() {     int y=128;     const int x=y;     printf("%d\n", x);     return 0; }

  • 128
  • Garbage value
  • Error
  • 0
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2. What will be the output of the program? #include<stdio.h> #include<stdlib.h> union employee {     char name[15];     int age;     float salary; }; const union employee e1; int main() {     strcpy(e1.name, "K");     printf("%s %d %f", e1.name, e1.age, e1.salary);     return 0; }

  • Error: RValue required
  • Error: cannot convert from 'const int *' to 'int *const'
  • Error: LValue required in strcpy
  • No error
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3. What will be the output of the program? #include<stdio.h> int fun(int **ptr); int main() {     int i=10;     const int *ptr = &i;     fun(&ptr);     return 0; } int fun(int **ptr) {     int j = 223;     int *temp = &j;     printf("Before changing ptr = %5x\n", *ptr);     const *ptr = temp;     printf("After changing ptr = %5x\n", *ptr);     return 0; }

  • Address of i Address of j
  • 10 223
  • Error: cannot convert parameter 1 from 'const int **' to 'int **'
  • Garbage value
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4. What will be the output of the program? #include<stdio.h> int main() {     const int x=5;     const int *ptrx;     ptrx = &x;     *ptrx = 10;     printf("%d\n", x);     return 0; }

  • 5
  • 10
  • Error
  • Garbage value
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5. What will be the output of the program in TurboC? #include<stdio.h> int fun(int **ptr); int main() {     int i=10, j=20;     const int *ptr = &i;     printf(" i = %5X", ptr);     printf(" ptr = %d", *ptr);     ptr = &j;     printf(" j = %5X", ptr);     printf(" ptr = %d", *ptr);     return 0; }

  • i= FFE2 ptr=12 j=FFE4 ptr=24
  • i= FFE4 ptr=10 j=FFE2 ptr=20
  • i= FFE0 ptr=20 j=FFE1 ptr=30
  • Garbage value
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6. What will be the output of the program? #include<stdio.h> int main() {     const char *s = "";     char str[] = "Hello";     s = str;     while(*s)         printf("%c", *s++);     return 0; }

  • Error
  • H
  • Hello
  • Hel
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7. What will be the output of the program? #include<stdio.h> int get(); int main() {     const int x = get();     printf("%d", x);     return 0; } int get() {     return 20; }

  • Garbage value
  • Error
  • 20
  • 0
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8. What will be the output of the program (in Turbo C)? #include<stdio.h> int fun(int *f) {     *f = 10;     return 0; } int main() {     const int arr[5] = {1, 2, 3, 4, 5};     printf("Before modification arr[3] = %d", arr[3]);     fun(&arr[3]);     printf("\nAfter modification arr[3] = %d", arr[3]);     return 0; }

  • Before modification arr[3] = 4 After modification arr[3] = 10
  • Error: cannot convert parameter 1 from const int * to int *
  • Error: Invalid parameter
  • Before modification arr[3] = 4
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9. What will be the output of the program? #include<stdio.h> int main() {     const int i=0;     printf("%d\n", i++);     return 0; }

  • 10
  • 11
  • No output
  • Error: ++needs a value
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10. What will be the output of the program? #include<stdio.h> int main() {     const c = -11;     const int d = 34;     printf("%d, %d\n", c, d);     return 0; }

  • Error
  • -11, 34
  • 11, 34
  • None of these
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