I am new to C++ . Is there any way that I can use the "for...else" method? I came from a python background there is a method called for...else loop
for n in range(2, 10):
for x in range(2, n):
if n % x == 0:
print( n, 'equals', x, '*', n/x)
break
else:
# loop fell through without finding a factor
print(n, 'is a prime number')
Is there any process in c++ like the "for...else" loop in python?
No, there is nothing equivalent to for-else of Python in C++.
There are a few alternatives to transform the function. I'll use a simpler example:
for i in range(a, b):
if condition(i):
break
else:
not_found()
The closest transformation can be achieved using goto, but you may find that some colleagues are likely to object (because goto is "evil" and scary):
for (int i = a; i < b; i++) {
if (condition(i)) {
goto found;
}
}
not_found();
found:;
Other alternatives, which are also possible in Python are to introduce an additional boolean variable and if:
bool found = false;
for (int i = a; i < b; i++) {
if (condition(i)) {
found = true;
break;
}
}
if (!found) {
not_found();
}
Or to encapsulate the whole thing within a function, which I think is the most widely accepted alternative both in Python and in C++.
void function()
{
for (int i = a; i < b; i++) {
if (condition(i)) {
return;
}
}
not_found();
}
You can achieve something similar. Simply add a branch to test if the exit condition for the loop is satisfied. Here is an example:
#include <cstdio>
int main() {
for (int n = 2; n < 10; ++n) {
int x = 2;
for (; x < n; ++x) {
if (n % x == 0) {
std::printf("%d equals %d * %d\n", n, x, n / x);
break;
}
}
if (x == n)
std::printf("%d is a prime number\n", n);
}
}