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The purpose of this article is to share with you the content of the sample analysis of scanf read cache in C language. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Preface

First of all, we need to understand what the scanf function is.

According to cplusplus.com 's explanation,

The definition of scanf function

The scanf () function is a general-purpose terminal formatting input function from a standard input device (keyboard).

Read the input information. You can read any inherent type of data and automatically convert the values to the appropriate in-machine format. The calling format is as follows:

Scanf ("",)

Function: perform formatted input

And note that the scanf () function returns the number of data items that were successfully assigned, and EOF if there is an error.

When you dig deeper (you don't need to know the principle for the time being, you just need to know the result)

You can get the following understanding:

The keyboard input is not read directly to scanf, but is temporarily stored in the buffer.

For example, a code like this:

# include int main () {int a, b, c, d, eport scanf ("% d% d", & a, & b, & c, & d); printf ("% d% d\ n", a, b, c, d); scanf ("% d", & e); printf ("% d\ n", e); return 0;}

Expected: 1 2 3 4

1 2 3 4

five

five

But if you type this: 1 2 3 4 5

Will output 1 2 3 4

five

This is because scanf uses the enter key as a signal to go to the buffer to read the data. As long as the format of the data meets the standard, it can be read correctly, otherwise it will have to wait for further input / read failure.

Summary

By consulting the website, we know that the scanf function is a standard input stream (receiving data from the keyboard), and the received data is put into the input buffer, including characters such as spaces and carriage returns entered on the keyboard.

But!

It will not affect when you receive with% d, but an error will occur with% c, because when entering "% c", spaces and escape characters are considered valid characters will be received by% c. Resulting in an output error, unable to AC

Solution method

1.List item

You can type a space before% c (optimal solution)

Eg:scanf (& c, & a)

Here% c is preceded by a space bar to eliminate all previous white space characters (this will be digested when typed) so that there is no need to use getchar () to swallow\ n

And there will be no hidden danger of leaving white space characters next time.

two。 Use getchar () to swallow\ n in the cache

While (ch=getchar ()! = EOF) getchar ()

Use getchar (); to swallow the remaining'\ n'in the cache so that the program can run properly

Thank you for reading! This is the end of this article on "sample analysis of scanf read cache in C language". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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