Question

I had learned that

inline ostream & _Cdecl ostream::operator<< (const signed char * _s) {
    outstr(_s, (const signed char *)0);
    return *this;
}

is how the insertion operator (<<) is declared(overloaded) in the iostream.h header file. Can I possibly use the same function to print a string value on screen?

I tried

#include<iostream.h>
int main() {
    outstr("Hello world!", (const signed char *)0);
    return 0;
}

it ended up in error. I would like to use something like this in order to see if there is some possible way to answer this query of printing something on screen without using printf, cout or puts().

Update: I would welcome if you have any suggestions other than

#include<stdlib.h>
void main() {
    system("echo /"Hello world!/"");
}

NB: I have no restrictions if you can provide the C equivalent code that can print without a printf(), cout or puts()

Answer 1

If you want portability across all standards compliant C++ implementations, you can print a string to standard output in the following ways

const char * str = "Hello World\n";
fprintf(stdout, str);
fputs(str, stdout);
for (int i=0; str[i]!=0; ++i)
    putchar(str[i]);
for (int i=0; str[i]!=0; ++i)
    putc(str[i], stdout);
for (int i=0; str[i]!=0; ++i)
    fputc(str[i], stdout);
fwrite(str, sizeof(*str), strlen(str), stdout);

Additionally, you can use std::cerr and std::clog. They write to stderr instead of stdout, but from the user’s perspective, that’s often the same place:

std::cerr << str;
std::clog << str;

From an efficiency perspective, I doubt any of these are going to help you. For that purpose, you might want to look at something a bit more platform specific. For POSIX systems, see the answer given by Dave S. For Windows, see this link.

What you shouldn’t do, is open up your header files and imitate what they use. At least, not at the middle levels, where they are using different various obscure functions within their own implementation. Those functions might not exist upon the next release. However, if you go to the deepest levels, you will find OS specific calls like the ones in the link I provided above. Those should be safe to use as long as you stay on the same OS, or even between OS versions.