GOTO is a statement of the early beginnings of programming. It is rarely used in high-level code today. Code that makes use of it is called Spaghetti code by some people. I have almost never seen goto statements in code, so I've been curious about them.
Python
Python does NOT offer GOTO. However, somebody made a GOTO module for April Fools' Day. See goto in Python if you're still interested.
Java
Java has no goto statement. Studies illustrated that goto is (mis)used more often than not simply "because it's there". Eliminating goto led to a simplification of the language--there are no rules about the effects of a goto into the middle of a for statement, for example. Studies on approximately 100,000 lines of C code determined that roughly 90 percent of the goto statements were used purely to obtain the effect of breaking out of nested loops. As mentioned above, multi-level break and continue remove most of the need for goto statements.
Source: java.sun.com
C++
GOTO works in C++. Here is a minimal example:
Minimal Example
#include <iostream>
using namespace std;
int main(){
int test = 0;
start:;
if (test > 10) {
goto end;
} else {
test += 7;
goto start;
}
end:;
cout << "test: " << test << endl;
return 0;
}
Output:
test: 14
Euclidean GCD algorithm
Most of you might know the euclidean algorithm for calculating the greatest common divisor in a version like this one:
#include <iostream>
using namespace std;
int euclidGCD(int a, int b) {
while (b != 0) {
int m = a % b;
a = b;
b = m;
}
return a;
}
int main(){
// Outputs 20
cout << "GCD of 340 and 32760: " << euclidGCD(340, 32760) <<endl;
return 0;
}
Here is a goto-version that works perfectly fine:
#include <iostream>
using namespace std;
int euclidGCD(int a, int b) {
if (b > a) goto b_larger;
while (1) {
a = a % b;
if (a == 0) return b;
b_larger:
b = b % a;
if (b == 0) return a;
}
}
int main(){
cout << "GCD of 340 and 32760: " << euclidGCD(340, 32760) <<endl;
return 0;
}
Source: literateprograms.org
Try bad things
You can't jump into a function:
#include <iostream>
using namespace std;
int myFunction(int i) {
i += 1;
inFunctionLabel:;
i += 1;
return i;
}
int main(){
int test = 0;
goto inFunctionLabel;
cout << "test: " << test << endl;
return 0;
}
Compiler error:
gotoExample.cpp: In function ‘int myFunction(int)’:
gotoExample.cpp:7: warning: label ‘inFunctionLabel’ defined but not used
gotoExample.cpp: In function ‘int main()’:
gotoExample.cpp:15: error: label ‘inFunctionLabel’ used but not defined
So goto is at least bound to its scope.