fgets是做什么的? [英] What does fgets do?

问题描述

不相等:

fgets (answer, 256, stdin);

if (strncmp(answer, "sta", 4) == 0)
  printf("omg, it's equal"); 

此代码是:

fgets (answer, 4, stdin);

if (strncmp(answer, "sta", 4) == 0)
  printf("omg, it's equal"); 

为什么?这是因为在第一个答案中，我猜第4个位没有\ 0(如果我将其更改为3而不是4则可以).但是，fgets的作用是什么?字符串答案中的第一个是str \whitespace*253\0"吗?第二个是str\0?谢谢.

Why? It is because in the first, answer doesn't have \0 at the 4th place I guess (if I change it to 3 instead of 4 it works). But what does fgets do? String answer in the first is str \whitespace*253\0"? And in the second it is str\0? Thank you.

推荐答案

fgets(与gets不同)包括尾随的\n，该末尾的\n对应于在行末按回车键.如果将3作为限制，它将截断字符串，并丢弃\n.

fgets (unlike gets) includes the trailing \n corresponding to the return pressed at the end of the line. If you put 3 as the limit it truncates the string, discarding the \n.

从联机帮助页:

fgets()从流中读取的字符数最多小于大小字符 将它们存储到s指向的缓冲区中.读取后停止 EOF或换行符.如果读取了换行符，则将其存储到缓冲区中. 终止空字节('\0')存储在的最后一个字符之后 缓冲区.

fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A terminating null byte ('\0') is stored after the last character in the buffer.

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