c语言变长数组

    传统的C语言是不能像C++那样支持变长数组的，也就是说数组的长度是在编译期就确定下来的，不能在运行期改变。C99标准定义的C语言新特性，新增的一项功能可以允许在C语言中使用变长数组。
　C99 gives C programmers the ability to use variable length arrays, which are arrays whose sizes are not known until run time. A variable length array declaration is like a fixed array declaration except that the array size is specified by a non-constant expression. When the declaration is encountered, the size expression is evaluated and the array is created with the indicated length, which must be a positive integer. Once created, variable length array cannot change in length. Elements in the array can be accessed up to the allocated length; accessing elements beyond that length results in undefined behavior. There is no check required for such out-of-range accesses. The array is destroyed when the block containing the declaration completes. Each time the block is started, a new array is allocated.
    以上就是C99标准对C语言变长数组的说明。