Stdlib: printf() — formatted output to stdout (ext/standard/formatted_print.c parity)

[PurHur]

Category

stdlib / runtime

Problem

sprintf() / vsprintf() are implemented, but printf() is missing — formatted writes to stdout fail at link/call time. Zend printf() shares the formatted_print.c engine with sprintf() and returns the number of bytes written.

php-src reference

• php/php-src ext/standard/formatted_print.c — PHP_FUNCTION(printf) → internal php_printf
• php/php-src ext/standard/sprintf.c — shared format parser (if split in tree)
• fprintf() stream variant — Stdlib: fprintf() — formatted write to stream (ext/standard/formatted_print.c parity) #3301
• Positional args %1$s — Stdlib: sprintf()/printf() positional arguments — %1$s reordering (ext/standard/sprintf.c parity) #3631

Repro (today)

<?php
$n = printf("%d %s\n", 42, 'ok');
var_dump($n);

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "\$n = printf(\"%d %s\\n\", 42, \"ok\"); var_dump(\$n);"'
php -r '$n = printf("%d %s\n", 42, "ok"); var_dump($n);'

Engine	stdout	Return
Zend	42 ok\n	int(7) (byte count)
This compiler	—	LogicException: Call to undefined function printf()

Error path (subset)

<?php
printf('%'); // Zend: Warning + false; document behavior

Scope (this repo)

Module	Path
VM	ext/standard/printf.php — delegate formatting to existing sprintf/VmString helper, echo/stdout write, return length
Module	ext/standard/Module.php
JIT	optional phase 2 — reuse sprintf JIT pieces if any
Tests	test/compliance/cases/stdlib/printf_basic.phpt
Matrix	script/capability-matrix.php

Implementation hint: mirror fprintf() design in #3301 but target SAPI stdout instead of stream resource.

Done when

• %d, %s, %f repro prints to stdout and returns correct byte length on VM
• printf registered in capability matrix (VM yes)
• ./script/ci-fast.sh --filter printf_basic green
• No regression on existing sprintf() compliance tests

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter printf_basic'

Related

• Stdlib: sprintf()/printf() positional arguments — %1$s reordering (ext/standard/sprintf.c parity) #3631 — positional %1$s (sprintf/printf family)
• Stdlib: fprintf() — formatted write to stream (ext/standard/formatted_print.c parity) #3301 — fprintf()
• Stdlib: vsprintf() and sscanf() — formatted I/O (ext/standard/sprintf.c parity) #3190 — vsprintf() / sscanf()

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Merged via #3902.

Verification: PrintfBuiltinTest, VMTest.*printf, AotTest.*printf — all green in Docker (./script/docker-exec.sh).

printf() uses the sprintf format subset (%s, %d, %f, %%); returns bytes written (Zend: int(6) for %d %s\n + 42 + ok).