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HP-UX Reference > F
feholdexcept(3M)HP-UX 11i Version 2: December 2007 Update |
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NAMEfeholdexcept() — save floating-point environment DESCRIPTIONThe feholdexcept() function saves the current floating-point environment in the object pointed to by the argument envp. This function also clears the floating-point exception flags and disables all traps. Use feholdexcept() with feupdateenv() to hide spurious floating-point exceptions. Use it with fesetenv() to hide all floating-point exceptions. USAGETo use this function, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options. Make sure your program includes <fenv.h>. For Itanium(R)-based systems, specify +Ofenvaccess on the compiler command line or place the call to this function under the effect of an affirmative FENV_ACCESS pragma: #pragma STDC FENV_ACCESS ON If the FENV_ACCESS pragma is placed outside of any top-level declarations in a file, the pragma will apply to all declarations in the compilation following the pragma until another FENV_ACCESS pragma is encountered or until the end of the file is reached. If the FENV_ACCESS pragma is placed at the beginning of a block (compound statement), the pragma will apply until another FENV_ACCESS pragma is encountered or until the end of the block is reached. For PA-RISC, you might need to use the +Onomoveflops compiler option in order to prevent optimizations that can undermine the specified behavior of this function. Link in the math library by specifying -lm on the compiler or linker command line. For more information, see the HP-UX Floating-Point Guide. RETURN VALUEThe feholdexcept() function returns a zero value, indicating the successful disabling of any traps. EXAMPLESStore the current floating-point environment in holdenv, hide spurious underflow exceptions, and continue on any floating-point exceptions that occur until the call to feupdateenv() is encountered. #include <fenv.h> /*...*/ fenv_t holdenv; feholdexcept(&holdenv); /* perform operations */ if (/* test for spurious underflow */) feclearexcept(FE_UNDERFLOW); feupdateenv(&holdenv); /* raise accumulated exceptions */ |
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