[PHP] substr占用内存谨慎使用

在下面的场景中使用substr的时候, 有时候会报超出内存fatal error ,当curl读取的内容过大的时候

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$header_size = curl_getinfo($curl_handle, CURLINFO_HEADER_SIZE); $this->response_headers = substr($this->response, 0, $header_size); $this->response_body = substr($this->response, $header_size); $this->response_code = curl_getinfo($curl_handle, CURLINFO_HTTP_CODE); $this->response_info = curl_getinfo($curl_handle);

用substr切分curl返回的内容 , 分出header头和body体

1. 测试一下:

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<?php $start=memory_get_usage(); $str="123"; var_dump(memory_get_usage()-$start); //$a=substr($str,0,1); $a=$str; var_dump(memory_get_usage()-$start-24); $b=$str; //$b=mb_substr($str,1); var_dump(memory_get_usage()-$start-24); $c=$str; //$b=mb_substr($str,1); var_dump(memory_get_usage()-$start-24);

这个变量赋值,占48字节

2.使用substr切分后

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<?php $start=memory_get_usage(); $str="123"; var_dump(memory_get_usage()-$start); //$a=substr($str,0,1); $a=$str; var_dump(memory_get_usage()-$start-24); //$b=$str; $b=substr($str,0,1); var_dump(memory_get_usage()-$start-24); //$c=$str; $c=substr($str,1); var_dump(memory_get_usage()-$start-24);

切分后赋值,占到了92字节 和 96字节 , 比原变量涨了一倍多