Example macros

Many of these are not optimal in terms of length, but serve as understandable explanations of different features. Try to read them in detail and understand what's happening!

For a more general introduction, especially for use as a calculator: Wikipedia article about dc. Many GNU dc scripts will still work, but most algorithms have significantly easier possible implementations.

I also have a repo of more advanced programs.

• Clear screen: [clear]\ on Linux &c, [cmd /c cls]\ on Windows
• Leave only the top object on the stack: zRz1-C or SacLa
• Infinite loop with constant memory usage (CPU stress test): [lax]salax
• Sum the entire stack: [+]z2-X
• Average the entire stack: zSa[+]la1-XLa/
• Absolute value: [_1*]s|d0>|
  • Has to use a register for the helper macro, leaves it there. Use d0>| on successive runs.
• Round down (positive only): d1+%
  • Rounding is a side effect of all commands that take integers.
• Factorial (assuming positive integer): d1-dSa[d1-]rX[*]LaX
• Recreate number (to apply W change): {"x}
• Crude "benchmark" of CPU speed (lower=better): [[timens]"]2Xr-P
• "Advanced" prompt (shows current params and prints stack on enter): [WOIK{["[ ]+n]4X}[> ]n?fl?x]S?l?x
• leftpad(str, len, ch) without registers: 3Rrdg_3R-_3Rr*r+
• Random character in the ASCII printable range: 95N32+a
  • 20-char password: [][95N32+a+]20X
• Random UUID: {16o[][ON"+]32X}8~[4~]3X[[-]r++]4X
  • 2 chars shorter than a UUID!
• Allocate ~30G of memory with the shortest macro possible: @9;a
• Check whether the thread on reg a has finished, run b if yes: Za0MaZa!=b
  • Assuming it should yield a result on its stack.

Four-dimensional byte storage

These can probably be optimized a lot.

A hashmap stores registers with arbitrary numbers. Each register is a stack of RegObjs. Each RegObj has an associated array. Each array cell can store a string, which can be manipulated char-wise.

• save(byte, reg, pos, idx, chr): S4S3S2_1@9+dS1,Zl2[[[]l1,S]l2l1,Z-1+X]S0!<0[l1,b1@9 1+,B]l1,Zl2-1-Xl3l1,;gl4[l3l1,;dgl4-1-0ar*+l3l1,:]s0!<0l3l1,;l4~_1-_3Rar++l3l1,:[1@9 1+,bl1,B]1@9 1+,ZXL4L3L2L1L05C
  • No checks for input ranges, all indices start at 0, register #s used for storage start at -999'999'999.
• load(reg, pos, idx, chr) -> byte: S4S3S2_1@9+dS1,Zl2[[[]l1,S]l2l1,Z-1+X]S0!<0[l1,b1@9 1+,B]l1,Zl2-1-Xl3l1,;gl4[l3l1,;dgl4-1-0ar*+l3l1,:]s0!<0l3l1,;l4%a[1@9 1+,bl1,B]1@9 1+,ZXL4L3L2L1L05C
  • Uninitialized cells return 0.

Interesting ways of quitting (try to find your own!)

To demonstrate the potential for obfuscation.

• 113ax - value of q
• 69 420 128|ax - peak comedy numbers, found the magic value of 128 using dc:im itself!
• 1.562 3tax - x tan grows rapidly close to xπ2/=
• zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzax - top-of-stack increment
• [6chrs ]19*1-gax - 6 19*114=
• [qxd]1~1~@8Xx - chain reaction using [x], needs ~10G of memory (@7 for lite version)