In C/C++, when a character array is initialized with a double quoted string and array size is not specified, compiler automatically allocates one extra space for string terminator ‘ ’. For example, following program prints 6 as output.
#include<stdio.h> int main() { // size of arr[] is 6 as it is ' ' terminated char arr[] = "geeks"; printf("%lu", sizeof(arr)); return 0; } |
Output :
6
If array size is specified as 5 in the above program then the program works without any warning/error and prints 5 in C, but causes compilation error in C++.
// Works in C, but compilation error in C++ #include<stdio.h> int main() { // arr[] is not terminated with ' ' // and its size is 5 char arr[5] = "geeks"; printf("%lu", sizeof(arr)); return 0; } |
Output :
5
When character array is initialized with comma separated list of characters and array size is not specified, compiler doesn’t create extra space for string terminator ‘ ’. For example, following program prints 5.
#include<stdio.h> int main() { // arr[] is not terminated with ' ' // and its size is 5 char arr[]= {'g', 'e', 'e', 'k', 's'}; printf("%lu", sizeof(arr)); return 0; } |
Output :
5
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