Difference between revisions of "cpp/utility/program/longjmp"
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| − | Loads the execution context {{tt|env}} saved by a previous call to {{ | + | Loads the execution context {{tt|env}} saved by a previous call to {{c|setjmp}}. This function does not return. Control is transferred to the call site of the macro {{c|setjmp}} that set up {{tt|env}}. That {{c|setjmp}} then returns the value, passed as the {{tt|status}}. |
| − | If the function that called {{ | + | If the function that called {{c|setjmp}} has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed) |
| − | No destructors for automatic objects are called. If replacing of {{tt|std::longjmp}} with {{ | + | No destructors for automatic objects are called. If replacing of {{tt|std::longjmp}} with {{c|throw}} and {{c|setjmp}} with {{c|catch}} would execute a non-trivial destructor for any automatic object, the behavior of such {{c|std::longjmp}} is undefined. |
===Parameters=== | ===Parameters=== | ||
{{param list begin}} | {{param list begin}} | ||
| − | {{param list item | env | variable referring to the execution state of the program saved by {{ | + | {{param list item | env | variable referring to the execution state of the program saved by {{c|std::setjmp}}}} |
| − | {{param list item | status | the value to return from {{ | + | {{param list item | status | the value to return from {{c|setjmp}}. If it is equal to {{c|0}}, {{c|1}} is used instead}} |
{{param list end}} | {{param list end}} | ||
Revision as of 21:55, 19 April 2012
Template:cpp/utility/program/sidebar
| Defined in header <csetjmp>
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| void longjmp( std::jmp_buf env, int status ); |
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Loads the execution context env saved by a previous call to setjmp. This function does not return. Control is transferred to the call site of the macro setjmp that set up env. That setjmp then returns the value, passed as the status.
If the function that called setjmp has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed)
No destructors for automatic objects are called. If replacing of std::longjmp with throw and setjmp with catch would execute a non-trivial destructor for any automatic object, the behavior of such std::longjmp is undefined.
Contents |
Parameters
| env | - | variable referring to the execution state of the program saved by std::setjmp |
| status | - | the value to return from setjmp. If it is equal to 0, 1 is used instead |
Return value
(none)
Example
Run this code
#include <iostream> #include <csetjmp> std::jmp_buf jumpBuffer; [[noreturn]] void a(int count) { std::cout << "a(" << count << ") called\n"; std::longjmp(jumpBuffer, count+1); // setjump() will return count+1 } int main() { int count = setjmp(jumpBuffer); if (count != 9) a(count); // This will cause setjmp() to exit }
Output:
a(0) called a(1) called a(2) called a(3) called a(4) called a(5) called a(6) called a(7) called a(8) called
See also
| saves the context (function macro) |
