5. Download and use of MSDN

Many students are learning C Language , face C There are so many keywords in the language 、 The operator 、 Library functions feel very big .

utilize MSDN This tool can help us understand them quickly .

Catalog

MSDN The download

MSDN Use

Indexes

Function introduction

Function structure

The header file

Return value Introduction

Example

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MSDN The download

The complete version of MSDN A very large , Many functions are not available to beginners .

Here is a simplified version for you on Baidu cloud MSDN, The link is permanent , For everyone to download .

Baidu cloud link ：MSDN （ Lite version size ：74.87.zip_ Free high speed download | Baidu SkyDrive - Share unlimited (baidu.com)

When the download is complete , Decompress the compressed package , double-click exe Can be installed .

MSDN Use

MSDN After installed , Double-click to run it .

• Indexes

function MSDN, Enter into MSDN In the interface .

Click... On the left side of the interface “ Indexes ”.（ Be careful ： It's the index , Not search ！！！） If the index is not found , Click the small arrow on the right to move the menu bar .

• Function introduction

After clicking the index , Enter the content we want to query in the blank space below . for example ：strlen

On the screen strlen And three other related functions , Here you just need to see strlen The information of .

Below the headline “Get the length of a string.” It's right strlen The explanation of , come to know strlen Is used to find the length of the string .

• Function structure

following , That's right strlen The use structure of .

size_t： Expressed as strlen The return value of is an unsigned integer .

const char* string： Cannot pair through pointer string Make changes , But you can use variable name pairs string Make changes .

char* const string： Cannot pass variable name pair string Make changes , But you can use the pointer to string Make changes .

Here to size_t as well as const char* string It doesn't matter if you don't understand , Remove them all , Just look at strlen(strlen); that will do .

• The header file

Under the structure introduction , It's called strlen The header file that the function needs to contain .

Find through the table , If the strlen function , Need to include header file <string.h>.Compatibility For compatibility , Don't know too much about , The computers we currently use are all compatible .

• Return value Introduction

Libraries Part of the content is ： Library files required by the program when it runs , Usually, the LIB or DLL The form provides , Don't pay too much attention to this part .

The next convenience is the introduction of the return value ：

Through the introduction, I learned ：strlen Returns the number of characters in a string , But it does not include terminals NULL（ No return ‘\0’）. When an error is reported , No value returned .

• Example

Slide the roller down ,MSDN It also gives us examples strlen How to use it? .

  Copy the above code , Paste into our VS in , Test whether it is with output The display is consistent .

#include <conio.h>
#include <dos.h>

These two lines of header files are actually useless , You can delete , And just now there is no display in the header file .

#include <string.h>
#include <stdio.h>


void main(void)
{
	char buffer[61] = "How long am I?";
	int  len;
	len = strlen(buffer);
	printf("'%s' is %d characters long\n", buffer, len);
}

Compare the , We can find that the output content is consistent .

Of course ,MSDN The example version in is older , A lot of writing is out of date , It is not recommended that you learn , The example just refers to how the function is used .