- Consider the following program:
#include <stdio.h> int main() { int a[10][20][30]={0}; printf("%ld",&a+1 - &a); return 0; }What is the output of this program?
- Consider the following program:
#include <stdio.h> int main() { int a[10][20][30] = {0}; int *b = a; int *c = a+1; printf("%ld", c-b); return 0; } What is the output of this program? (You may ignore compiler warnings) - What is the output of the following program?
#include <stdio.h> #include <stdlib.h> int* fun(); int main() { int *a = fun(); printf("%d",*a); return 0; } int* fun() { int *a =(int*) malloc(sizeof(int)); *a = 10; return a; } - What is the output of the following program?
#include <stdio.h> int main() { int *a = fun(); printf("%d",a); return 0; } int fun() { int a = 10; return a; } - What is the output of the following program?
#include <stdio.h> #include <string.h> int main() { char string[] = "Hello"; printf("%zu %zu",sizeof(string),strlen(string)); return 0; } - What is the output of the following program?
#include <stdio.h> int main() { float a = 0.5; if(a == 0.5) printf("Yes"); else printf("No"); return 0; } - What is the output of the following program?
#include <stdio.h> #include <string.h> void foo(char *); int main() { char a[100] = {0}; printf("%zu %zu",sizeof(a),strlen(a)); return 0; } - What is the output of the following program? (Assume input is 10)
#include <stdio.h> int main() { int a; printf("%d",scanf("%d",&a)); return 0; } - If the binary equivalent of 5.375 in normalised form is 01000000 10101100 00000000 00000000, what will be the output of the following program?
#include <stdio.h> int main() { float a=5.375; char *p; int i; p = (char*)&a; for(i=0; i<2; i++) printf("%x", (unsigned char)(p[i]^p[3-i])); return 0; } - What is the output of the following program?
#include <stdio.h> int main() { char str[] = {'a','b','c','\0'}; str[0] -= 32; printf("%s",str); return 0; }
Questions from Datatypes
- Consider an implementation where int is 4 bytes and long int is 8 bytes. Which of the following initializations are correct?
#include <stdio.h> int main() { long int a = 0x7fffffff * 0x7ffffff; long int b = 0x7ffffffff * 0x7ffffff; long int c = 0x7fffffff * 0x7fffffff; long int d = 0x7fffffff * 0x7fffffffl; printf("a = %ld, b = %ld, c = %ld, d = %ld\n", a, b, c, d); return 0; } - Consider an implementation where int is 4 bytes and long int is 8 bytes. What will be the output of the following code?
#include <stdio.h> int main() { int i = 0; size_t a = sizeof i, b = sizeof (long); printf("a = %zd, b = %zd\n", a, b); //If %zd is given the compiler will automatically give it the correct type whether short, long or normal. This is useful for special data types like size_t whose size is implementation specific return 0; } - What will be the output of the following code?
#include <stdio.h> int main() { unsigned int a = 5; if(a > -1) printf("5 is > -1\n"); return 0; } - What will be printed by the following code?
#include <stdio.h> int main() { char buff[255] = "abc\ pee"; printf("%s", buff); return 0; } - What will be printed by the following code?
#include <stdio.h> int main() { char buff[255] = "\0"; printf("%s", buff); return 0; } - What will be the output of the following code? (Assume a 64 bit machine/compiler)
#include <stdio.h> int main() { char *p = "Hello World"; char q[] = "Hello World"; printf("%zd %zd", sizeof p, sizeof *p); printf("\n"); printf("%zd %zd", sizeof q, sizeof *q); return 0; } - What will be the output of the following code?
#include <stdio.h> int main() { { char a = 5; int b = 5; if(a == b) printf("char and int compared equal\n"); } { int a = 5; long int b = 5; if(a == b) printf("int and long compared equal\n"); } { float a = 5.0; double b = 5.0; if(a == b) printf("float and double compared equal\n"); } { float a = 5.2; double b = 5.2; if(a == b) printf("float and double again compared equal\n"); } { float a = 5.2; if(a == 5.2) printf("float compared equal with constant\n"); } { double a = 5.2; if(a == 5.2) printf("double compared equal with constant\n"); } return 0; }
Questions from Pointers
- What will be the output of the following code?
#include <stdio.h> int main() { int a = 5; int* p = &a; printf("%d", ++*p); } - What will be the output of the following code?
#include <stdio.h> int main() { char a[] = "Hello World"; char* p = &a; printf("%s", p+2 ); } - What will be the output of the following code?
#include <stdio.h> int main() { int a; int* p = &a; printf("%zu", sizeof( *(char*)p )); } - Is the following code legal?
#include <stdio.h> int main() { int a = 1; if((char*) &a) { printf("My machine is little endian"); } else { printf("My machine is big endian\n"); } } - What will be the output of the following code?
#include <stdio.h> int main() { int *a = (int*) 1; printf("%d", a); } - What will be the output of the following code?
#include <stdio.h> int main() { int a = 1, *p, **pp; p = &a; pp = p; printf("%d", **pp); } - What will be the output of the following code?
#include <stdio.h> int main() { int a = 1, *p, **pp; p = &a; pp = p; printf("%d", *pp); } - Assuming a little endian machine, what will be the output of the following program?
#include <stdio.h> fun(int a) { char *arr[] = {"0000", "0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"}; unsigned char* p = (unsigned char*) &a ; p+=3; int i; for(i = 0; i < sizeof a; i++) { int d = (*p)>>4; printf("%s", arr[d]); d = (*p) & 0xf; printf("%s ", arr[d]); p--; } } int main() { int a; scanf("%d", &a); fun(a); }
Some codes
- What is the following function doing?
int foo(int n) { int sum = 0; while(n > 0) { n = n & n-1; sum++; } return sum; } - What is the following function doing?
int foo(int a, int b) { int c = a, d = b; while(a != b) { if(a < b) a = a+c; else b = b+d; } return a; } - What is the following function doing?
int foo( int a, int b) { int c = a-b; c = c&(0x80000000); return (!c)*a +(!!c)*b; } - What is the following function doing?
unsigned fun(unsigned a, unsigned b) { int i; unsigned j = 0; for(i = 0; i < 32; i++) { j <<= 1; j += !!(a & 0x80000000); a <<= 1; if(j >=b) { j -= b; a++; } } return a; } - What is the following function doing?
unsigned fun(unsigned int a) { unsigned int i, x = 0, y = 0, z = 0; for(i = 0; i < 16; i++) { y <<= 2; y += !!(a & 0x80000000) << 1; y += !!(a & 0x40000000); a <<= 2; x = x + (x&1); x <<= 1; z <<= 1; if(x + 1 <= y) { x++; z++; y-=x; } } return z; } - Write the code to dynamically allocate a 2-D array of size m x n.
- Declare a pointer to a function accepting an integer and returning void.
- Write the condition so that the below code outputs Hello World.
#include <stdio.h> int main() { if() { printf("Hello "); } else { printf("World\n"); } return 0; } - Write a one line code to check if a number is a power of 2.
- Write a one line code to invert the last four bits of an integer.
