PHP performance analysis (001)-str_repeat ($ input, $ multiplier)

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  * 1. memcpy and memmove are used, with the highest efficiency. ** @ Param number $ levelNum * number of pyramid layers: default 20 * @ return string pyramid result */functiongetEmptyJinZiTa ($ levelNum = 20) {$ SPACE = ""; // fill in space $ STAR = "*"; // fill in the space at the beginning of the first line of the model $ decreseSpace = $ levelNum-1, decrease by line $ result = ""; for ($ level = 1; $ level <= $ levelNum; ++ $ level) {// number of layers outside the loop $ result. = str_repeat ($ SPACE, $ decreseSpace --); if ($ level >=1 & $ level <$ levelNum) {$ result. = $ STAR; $ spaceNum = ($ level -1) * 2-1; $ result. = str_repeat ($ SPACE, $ spaceNum <0? 0: $ spaceNum); if ($ level! = 1) // The first line is a * $ result. = $ STAR;} elseif ($ level = $ levelNum) {// The bottom layer needs to be fully filled * $ result. = str_repeat ($ STAR, $ level * 2-1);} $ result. ="
";}Return $ result;} echo getEmptyJinZiTa (); // Print the key content of the pyramid?>

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