First, it isn't too good of an idea to use using namespace std; as discussed herehere. There are times and places to use it, but you should know about this.
Second, it is obvious you are using VC++ (which isn't bad, but isn't exactly the same as C++). You should write your main like this instead:
int main() I'm not sure what the h and bl names are supposed to mean (height and baseline?), use descriptive names.
This can be a for loop:
while (h != 0) { Write it like this:
for (int height = 20; height > 0; --height) { for (int i = 0; i != height; i++) { cout << " "; } for (int i = 0; i != bl; i++) { cout << "*"; } cout << endl; bl = bl + 2; } In fact, you can even put the bl variable in the loop too:
for (int height = 20, baseline = 1; height > 0; --height, baseline += 2) { for (int i = 0; i != height; i++) { cout << " "; } for (int i = 0; i != baseline; i++) { cout << "*"; } cout << endl; } Use the prefix ++ and -- operators whenever possible because the postfix operators have worse performanceworse performance due to the need for them to create a copy of the object to return before incrementing the value.
for (int i = 0; i < baseline; ++i) { Also, in a loop like this, you typically do i < baseline, not i != baseline.
If you want to remove the inner loops entirely, you can rewrite the entire program to just this:
for (int height = 20, baseline = 1; height > 0; --height, baseline += 2) { std::cout << std::string(height, ' ') << std::string(baseline, '*') << std::endl; } 