Transfers control unconditionally.

Used when it is otherwise impossible to transfer control to the desired location using other statements.

[edit]Syntax

[edit]Explanation

Thegoto statement transfers control to the location specified bylabel. Thegoto statement must be in the same function as thelabel it is referring, it may appear before or after the label.

If transfer of control exits the scope of any automatic variables (e.g. by jumping backwards to a point before the declarations of such variables or by jumping forward out of a compound statement where the variables are scoped), the destructors are called for all variables whose scope was exited, in the order opposite to the order of their construction.

Thegoto statement cannot transfer control into acontrol-flow-limited statement, but can transfer control out of a control-flow-limited statement (the rules above regarding automatic variables in scope are followed).

If transfer of control enters the scope of any automatic variables (e.g. by jumping forward over a declaration statement), the program is ill-formed (cannot be compiled), unless all variables whose scope is entered have the following types:

• scalar types declared without initializers
• class types with trivial default constructors and trivial destructors declared without initializers
• cv-qualified versions of one of the above
• arrays of one of the above

(Note: the same rules apply to all forms of transfer of control)

[edit]Notes

In the C programming language, thegoto statement has fewer restrictions and can enter the scope of any variable other thanvariable-length array or variably-modified pointer.

[edit]Keywords

goto

[edit]Example

#include <iostream> struct Object{// non-trivial destructor    ~Object(){std::cout<<'d';}}; struct Trivial{double d1;double d2;};// trivial ctor and dtor int main(){int a=10; // loop using gotolabel:    Object obj;std::cout<< a<<' ';    a-=2; if(a!=0)goto label;// jumps out of scope of obj, calls obj destructorstd::cout<<'\n'; // goto can be used to efficiently leave a multi-level (nested) loopsfor(int x=0; x<3;++x)for(int y=0; y<3;++y){std::cout<<'('<< x<<','<< y<<") "<<'\n';if(x+ y>=3)goto endloop;} endloop:std::cout<<'\n'; goto label2;// jumps into the scope of n and t [[maybe_unused]]int n;// no initializer [[maybe_unused]] Trivial t;// trivial ctor/dtor, no initializer //  int x = 1;   // error: has initializer//  Object obj2; // error: non-trivial dtor label2:{        Object obj3;goto label3;// jumps forward, out of scope of obj3} label3:std::cout<<'\n';}

10 d8 d6 d4 d2(0,0)(0,1)(0,2)(1,0)(1,1)(1,2) dd

[edit]See also

[edit]External links

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