Scope/Function names and labels: Difference between revisions
→{{header|Erlang}}
Line 31:
9000 DEF FN C(A)=A*A*A
9999 RETURN</lang>
=={{header|C}}==
Demonstrating function scope as well as goto in a C program invariably leads to code like the one below. The [http://en.wikipedia.org/wiki/Scope_(computer_science)#C Wikipedia article] is a good starting point.
<lang C>
/*Abhishek Ghosh, 8th November 2013, Rotterdam*/
#include<stdio.h>
#define sqr(x) x*x
#define greet printf("\nHello There !");
int twice(int x)
{
return 2*x;
}
int main()
{
int x;
printf("\nThis will demonstrate function and label scopes.");
printf("\nAll output is happening throung printf(), a function declared in the header file stdio.h, which is external to this program.");
printf("\nEnter a number : ");
scanf("%d",&x);
switch(x%2){
default:printf("\nCase labels in switch statements have scope local to the switch block.");
case 0: printf("\nYou entered an even number.");
printf("\nIt's square is %d, which was computed by a macro. It has global scope within the program file.",sqr(x));
break;
case 1: printf("\nYou entered an odd number.");
goto sayhello;
jumpin: printf("\n2 times %d is %d, which was computed by a function defined in this file. It has global scope within the program file.",x,twice(x));
printf("\nSince you jumped in, you will now be greeted, again !");
sayhello: greet
if(x==-1)goto scram;
break;
};
printf("\nWe now come to goto, it's extremely powerful but it's also prone to misuse. It's use is discouraged and it wasn't even adopted by Java and later languages.");
if(x!=-1){
x = -1; /*To break goto infinite loop.*/
goto jumpin;
}
scram: printf("\nIf you are trying to figure out what happened, you now understand goto.");
return 0;
}
</lang>
Showing an example run.
<pre>
This will demonstrate function and label scopes.
All output is happening throung printf(), a function declared in the header file stdio.h, which is external to this program.
Enter a number : 5
You entered an odd number.
Hello There !
We now come to goto, it's extremely powerful but it's also prone to misuse. It's use is discouraged and it wasn't even adopted by Java and later languages.
2 times -1 is -2, which was computed by a function defined in this file. It has global scope within the program file.
Since you jumped in, you will now be greeted, again !
Hello There !
If you are trying to figure out what happened, you now understand goto.
</pre>
=={{header|Erlang}}==
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