I want a 20 character NULL('\0') terminating string filled with white spaces.
Currently I am doing it in following way
char foo[20];
for (i = 0; i < num_space_req; i++) //num_space_req < 20
{
foo[i] = ' ';
}
foo[num_space_req] = '\0';
Is there a better way for above?
You can use the following to initialize the array to spaces:
memset(foo, ' ', num_space_req);
foo[num_space_req] = '\0';
std::string foo(num_space_req,' ');
Since the question has a C++ tag, the idiomatic way would be:
std::fill(foo, foo + num_space_req, ' ');
// or
std::fill_n(foo, num_space_req, ' ');
Note that it doesn't work in C.
You may use memset for that kind of thing.
memset (foo, ' ', num_space_req)
As @OliCharlesworth said, the best way is to use memset:
char bla[20];
memset(bla, ' ', sizeof bla - 1);
bla[sizeof bla - 1] = '\0';
Note that in GNU C, you can also use the following extension (range designated initializers):
char bla[20] = {[0 ... 18] = ' ', [19] = '\0'};
If you want the array initialized at compile time, you can modify your char foo[20]; declaration as follows:
char foo[20] = {0x20};
If you need to initialize the array to spaces at run time, then you can use the following:
memset(foo, ' ', sizeof(foo) -1);
foo[20] = '\0';
memset MIGHT be better optimised than your for loop, it might be exactly the same. pick one of:
memset( foo, ' ', sizeof(foo) -1 );
memset( foo, ' ', 19 );
memset( foo, ' ', 19 * sizeof(char) );
#include <cstring>
void makespace(char *foo, size_t size) {
memset((void*)&foo, ' ', size - 1);
foo[size] = 0;
}
// ...
makespace(foo, 20);
std::fill (foo, foo + num_space_req, ' ');