php数组转成json格式的方法

function array_to_json( $array ){
??? if( !is_array( $array ) ){
??????? return false;
??? }
??? $associative = count( array_diff( array_keys($array),array_keys( array_keys( $array )) ));
??? if( $associative ){
??????? $construct = array();
??????? foreach( $array as $key => $value ){
??????????? // We first copy each key/value pair into a staging array,
??????????? // formatting each key and value properly as we go.
??????????? // Format the key:
??????????? if( is_numeric($key) ){
??????????????? $key = "key_$key";
??????????? }
??????????? $key = "'".addslashes($key)."'";
??????????? // Format the value:
??????????? if( is_array( $value )){
??????????????? $value = array_to_json( $value );
??????????? } else if( !is_numeric( $value ) || is_string( $value ) ){
??????????????? $value = "'".addslashes($value)."'";
??????????? }
??????????? // Add to staging array:
??????????? $construct[] = "$key: $value";
??????? }
??????? // Then we collapse the staging array into the JSON form:
??????? $result = "{ " . implode( ",",$construct ) . " }";
??? } else { // If the array is a vector (not associative):
??????? $construct = array();
??????? foreach( $array as $value ){
??????????? // Format the value:
??????????? if( is_array( $value )){
??????????????? $value = array_to_json( $value );
??????????? } else if( !is_numeric( $value ) || is_string( $value ) ){
??????????????? $value = "'".addslashes($value)."'";
??????????? }
??????????? // Add to staging array:
??????????? $construct[] = $value;
??????? }
??????? // Then we collapse the staging array into the JSON form:
??????? $result = "[ " . implode( ",$construct ) . " ]";
??? }
??? return $result;
}