是否有和没有括号循环使用C不同的方式处理？ [英] Are loops with and without parenthesis handled differently in C?

问题描述

我是通过在调试一些C / CUDA code，像踩着

I was stepping through some C/CUDA code in the debugger, something like:

for(uint i = threadIdx.x; i < 8379; i+=256) 
    sum += d_PartialHistograms[blockIdx.x + i * HISTOGRAM64_BIN_COUNT];

和我心乱如麻，因为调试是在一步路过它，虽然输出是正确的。我意识到，当我把花括号我的循环如下面的代码片段，它像预期的那样表现调试

And I was utterly confused because the debugger was passing by it in one step, although the output was correct. I realised that when I put curly brackets around my loop as in the following snippet, it behaved in the debugger as expected.

for(uint i = threadIdx.x; i < 8379; i+=256) {
    sum += d_PartialHistograms[blockIdx.x + i * HISTOGRAM64_BIN_COUNT];
}

所以是括号，免费在C或调试器区别对待的循环，或者是特别CUDA。

So is are parenthesis-free for loops treated differently in C or in the debugger, or perhaps it is particular to CUDA.

感谢

推荐答案

在调试器将执行一个语句在一个时间。检查了这一点：

The debugger executes one statement at a time. Check this out:

int sum = 0;                            /* one assignment statement */
for (int k = 0; k < 10; k++) sum += k;  /* one for statement */

和与此比较

int sum = 0;                            /* one assignment statement */
for (int k = 0; k < 10; k++)
{                                       /* for statement with the body
                                           in a block of statements */
    sum += k;                           /* assignment statement */
}

在上面的第一个例子中，总和+ = K 是为语句的一个组成部分;在第二个例子中，它本身就是一个完整的声明。

In the first example above, the sum += k is an integral part of the for statement; in the 2nd example, it is a full statement on its own.

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