pop
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## pop

pop — Pops values from the global stack.

## Description

Pops values from the global stack.

## Syntax

    xval1, [xval2, ... , xval31] pop

    ival1, [ival2, ... , ival31] pop

## Initialization

ival1 ... ival31 - values to be popped from the stack.

## Performance

xval1 ... xval31 - values to be popped from the stack.

The given values are poped from the stack. The global stack works in LIFO order: after multiple push calls, pop should be used in reverse order.

Each push or pop operation can work on a "bundle" of multiple variables. When using pop, the number, type, and order of items must match those used by the corresponding push. That is, after a 'push Sfoo, ibar', you must call something like 'Sbar, ifoo pop', and not e.g. two separate 'pop' statements.

push and pop opcodes can take variables of any type (i-, k-, a- and strings). Use of any combination of i, k, a, and S types is allowed. Variables of type 'a' and 'k' are passed at performance time only, while 'i' and 'S' are passed at init time only.

push/pop for a, k, i, and S types copy data by value. By contrast, push_f only pushes a "reference" to the f-signal, and then the corresponding pop_f will copy directly from the original variable to its output signal. For this reason, changing the source f-signal of push_f before pop_f is called is not recommended, and if the instrument instance owning the variable that was passed by push_f is deactivated before pop_f is called, undefined behavior may occur.

Any stack errors (trying to push when there is no more space, or pop from an empty stack, inconsistent number or type of arguments, etc.) are fatal and terminate performance.

## See also

## Examples

Here is an example of the pop opcode. It uses the file pop.csd.

Example 563. Example of the pop opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    -odac   ;;;realtime audio out
    ;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
    ; For Non-realtime ouput leave only the line below:
    ; -o pop.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    sr = 44100
    ksmps = 32
    0dbfs  = 1
    nchnls = 2

    stack 100000

    instr 1

    a1	oscils 0.7, 220, 0
    k1	line 0, p3, 1
            push "blah", 123.45, a1, k1
            push rnd(k1)

    k_rnd	pop
    S01, i01, a01, k01 pop
            printf_i "S01 = '%s', i01 = %g\n", 1, S01, i01
    ktrig	metro 5.0
            printf "k01 = %.3f, k_rnd = %.3f\n", ktrig, k01, k_rnd
            outs a01, a01

    endin
    </CsInstruments>
    <CsScore>

    i 1 0 5
    e
    </CsScore>
    </CsoundSynthesizer>

stack, push, pop_f and push_f.

Using this opcode is somewhat hackish, as you can read here: http://csound.1045644.n5.nabble.com/passing-a-string-to-a-UDO-td1099284.html

## Credits

By: Istvan Varga.

2006

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