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Q.

union test

{
int x;
char arr[4];
int y;
};
int main()
{
union test t;
t.x = 0;
t.arr[1] = 'G';
printf("%s ", t.arr);
return 0;
}
Predict the output of above program. Assume that the size of an integer is 4 bytes and size of character is 1 byte. Also assume that there is no alignment needed.

A. Nothing is printed B. G
C. Garbage character followed by 'G' D. Garbage character followed by 'G', followed by more garbage characters

Answer: Option A
Explaination:

Since x and arr[4] share the same memory, when we set x = 0, all characters of arr are set as 0. O is ASCII value of '\0'. When we do "t.arr[1] = 'G'", arr[] becomes "\0G\0\0". When we print a string using “%s”, the printf function starts from the first character and keeps printing till it finds a \0. Since the first character itself is \0, nothing is printed.


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