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<?php function cele_cislo($cislo) { return preg_match('/^[1-9]\d*$/', $cislo) === 1; } var_dump(cele_cislo('123456f')); var_dump(cele_cislo('f123456')); var_dump(cele_cislo('123456'));
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.6 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.14
bool(false) bool(false) bool(true)

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179.42 ms | 408 KiB | 5 Q