note 97401 modified in function.substr-replace by danbrown

It's worth noting that when start and length are both negative -and- the length is less than or equal to start, the length will have the effect of being set as 0. <?php substr_replace('eggs','x',-1,-1); //eggxs substr_replace('eggs','x',-1,-2); //eggxs substr_replace('eggs','x',-1,-2); //eggxs ?> Same as: <?php substr_replace('eggs','x',-1,0); //eggxs ?> <?php substr_replace('huevos','x',-2,-2); //huevxos substr_replace('huevos','x',-2,-3); //huevxos substr_replace('huevos','x',-2,-3); //huevxos ?> Same as: <?php substr_replace('huevos','x',-2,0); //huevxos ?> Another note, if length is negative and start offsets the same position as length, length (yet again) will have the effect as being set as 0. (Of course, as mentioned in the manual, when length is negative it actually represents the position before it) <?php substr_replace('abcd', 'x', 0, -4); //xabcd ?> Same as: <?php substr_replace('abcd','x',0,0); //xabcd ?> <?php substr_replace('abcd', 'x', 1, -3); //axbcd ?> Same as: <?php substr_replace('abcd', 'x', 1, 0); //axbcd ?> --was-- It's worth noting that when start and length are both negative -and- the length is less than or equal to start, the length will have the effect of being set as 0. substr_replace('eggs','x',-1,-1); //eggxs substr_replace('eggs','x',-1,-2); //eggxs substr_replace('eggs','x',-1,-2); //eggxs Same as: substr_replace('eggs','x',-1,0); //eggxs substr_replace('huevos','x',-2,-2); //huevxos substr_replace('huevos','x',-2,-3); //huevxos substr_replace('huevos','x',-2,-3); //huevxos Same as: substr_replace('huevos','x',-2,0); //huevxos Another note, if length is negative and start offsets the same position as length, length (yet again) will have the effect as being set as 0. (Of course, as mentioned in the manual, when length is negative it actually represents the position before it) substr_replace('abcd', 'x', 0, -4); //xabcd Same as: substr_replace('abcd','x',0,0); //xabcd substr_replace('abcd', 'x', 1, -3); //axbcd Same as: substr_replace('abcd', 'x', 1, 0); //axbcd http://php.net/manual/en/function.substr-replace.php