ftruncate 将文件截断到指定的长度 &reftitle.description; boolftruncate resourcestream intsize 接受文件指针 stream 作为参数，并将文件大小截取为 size。 &reftitle.parameters; stream 文件指针。 stream 必须打开写入。 size 截断的大小。 If size is larger than the file then the file is extended with null bytes. If size is smaller than the file then the file is truncated to that size. &reftitle.returnvalues; &return.success; &reftitle.examples; ]]> &reftitle.notes; 文件指针不会改变。 &reftitle.seealso; fopen fseek