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copied!<p>Function arguments ("parameters") need not be stored at all. Remember: C uses <em>call by value</em>. A value need not be stored in a memory location, it could live in a register, or its value may be concluded from the program state in some way.</p> <p>For example, library functions like strlen() or sin() , cos(), sqrt() could be implemented in hardware. sin(x) <em>could</em> be implemented by storing some value(s) that correspond to <code>x</code> into special-function registers, issuing a special-function instruction and pulling the result out. (floating point hardware sometimes even has pseudo-instructions to represent for instance Pi in the best possible precision. The Pi value is never passed, only the instruction: "use Pi/2")</p> <p>Even for "normal" user-defined functions, the arguments could be passed via registers, multiple arguments <em>could</em> be combined into a large register, maybe even optimised out.</p> <p>This is best visible with inlined functions, these can totally disappear, because their functionality has been combined with that of the caller.</p> <p>Things get different when the function takes the address of one of its arguments (for instance <code>int func(int arg) { int *p = &arg; }</code> will force arg to have an address), but this case is relatively rare.</p> <p>WRT the standard: a C function has an <em>activation record</em>. (Non-standard people would probably call it a "stack frame"). And the function behaves <em>as if</em> the arguments are part of its local variables, and they go out of scope once the function returns. <em>How</em> they get their values is totally irrelevant, theoretically it could even be done by message passing. </p>

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