Govt Exams
The stdio.h header file contains declarations for standard input/output functions like printf() and scanf().
In a struct, each member has its own memory allocation, so the total size is the sum of all members. In a union, all members share the same memory location, so the size equals the largest member. Only one member can hold a value at a time in a union.
#define MAX 5
int main() {
int arr[MAX];
printf("%d", sizeof(arr)/sizeof(arr[0]));
return 0;
}
int arr[3][3] = {{1,2,3}, {4,5,6}, {7,8,9}};
int *ptr = (int *)arr;
printf("%d", *(ptr + 5));
A 2D array is stored in row-major order in memory: 1,2,3,4,5,6,7,8,9. When ptr is cast to int*, ptr+5 points to the 6th element (0-indexed), which is 6.
Both declarations are equivalent. 'const int * const ptr' and 'int const * const ptr' declare a constant pointer to a constant integer. The first const makes the integer constant, the second const makes the pointer constant.
#include
int main() {
int a = 5;
printf("%d %d %d", a++, ++a, a);
return 0;
}
This code contains undefined behavior because variable 'a' is modified multiple times (a++, ++a) without intervening sequence points in the same expression. The order of evaluation is unspecified, making the result compiler-dependent.
int x = 10;
int y = 20;
int z = x < y ? x++ : y++;
printf("%d %d %d", x, y, z);
A static variable declared inside a function has local scope (visible only within that function) but persists for the entire program lifetime. Its value is retained between function calls and is initialized only once.
int arr[] = {10, 20, 30};
int *ptr = arr;
printf("%d", *(ptr + 1));
ptr points to arr[0]. ptr + 1 points to arr[1]. *(ptr + 1) dereferences to get the value at arr[1] which is 20. Pointer arithmetic adds sizeof(int) to the address for each increment.
strcpy() does not perform bounds checking. If the source string is longer than the destination buffer, it will write beyond the buffer boundary, causing a buffer overflow. This is a security vulnerability. Using strncpy() is safer.