C language GOTO things you don't know
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Error Code
#include <stdio.h>
int main()
{
int a=1,b=2;
goto End;
int c[b];
End:
return 0;
}
Compiler error content
In function 'main':[Error] jump into scope of identifier with variably modified type
[Note] label 'End' defined here
[Note] 'c' declared here
Why does it appear
根据C11标准：
A goto statement is not allowed to jump past any declarations of objects with variably modified types. A jump within the scope, however, is permitted.
That is to say, the code between the goto statement and the "label" is not allowed to have variable-length array declaration statements. Because goto is an unconditional jump statement, the address needs to be determined at compile time. If the variable-length array is sandwiched in it, the compiler cannot determine the address.
The following codes are correct
#include <stdio.h>
int main()
{
goto End;
int a=1,b=2;
int c[2];
End:
return 0;
}
How to deal with it
Move the definition of variable-length arrays outside the scope of "goto-tag"
#include <stdio.h>
int main()
{
int a=1,b=2;
int c[a];
Begin:
goto End;
End:
return 0;
}
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