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GNU Info (mysql.info)mysql_fetch_lengths`mysql_fetch_lengths()' ....................... `unsigned long *mysql_fetch_lengths(MYSQL_RES *result)' Description ........... Returns the lengths of the columns of the current row within a result set. If you plan to copy field values, this length information is also useful for optimization, because you can avoid calling `strlen()'. In addition, if the result set contains binary data, you _must_ use this function to determine the size of the data, because `strlen()' returns incorrect results for any field containing null characters. The length for empty columns and for columns containing `NULL' values is zero. To see how to distinguish these two cases, see the description for `mysql_fetch_row()'. Return Values ............. An array of unsigned long integers representing the size of each column (not including any terminating null characters). `NULL' if an error occurred. Errors ...... `mysql_fetch_lengths()' is valid only for the current row of the result set. It returns `NULL' if you call it before calling `mysql_fetch_row()' or after retrieving all rows in the result. Example ....... MYSQL_ROW row; unsigned long *lengths; unsigned int num_fields; unsigned int i; row = mysql_fetch_row(result); if (row) { num_fields = mysql_num_fields(result); lengths = mysql_fetch_lengths(result); for(i = 0; i < num_fields; i++) { printf("Column %u is %lu bytes in length.\n", i, lengths[i]); } } automatically generated by info2www version 1.2.2.9 |