Comparison and use of sscanf and scanf

Sscanf ()-read data that matches the specified format from a string.

Function prototype:

Int sscanf (const char *, const char *,...);
Int scanf (const char *,...);

Header file:

# Include <stdio. h>

Note:

Similar to scanf, sscanf is used for input, but the latter uses the keyboard (stdin) as the input source, and the former uses a fixed string as the input source.

The first parameter can be one or more {% [*] [width] [{H | L | i64 | L}] type | ''| '/T' | '/ n' | non-% sign}

Note:

1. * can also be used in the format. (% * D and % * s) with an asterisk (*) indicates skipping this data and not reading it. (that is, do not read this data into the parameter)

2. {A | B | c} indicates A, B, and C. Select [d], which indicates D or D.

3. width indicates the read width.

4. {H | L | i64 | L}: parameter size. Generally, h indicates a single-byte size, I indicates a 2-byte size, and l indicates a 4-byte size (double exception ), l64 indicates 8-byte size.

5. Type: this is a lot, such as % s and % d.

6. Special: % * [width] [{H | L | i64 | L}] type indicates that values that meet this condition are filtered out and no value is written to the target parameter.

Collection operations are supported:

% [A-Z] indicates matching any character in A to Z, greedy (as many as possible)

% [AB '] matches a, B, and', greedy

% [^ A] matches any character other than a, greedy

 

Example: 1. Common usage.

Char Buf [512] =;

Sscanf ("123456", "% s", Buf );

Printf ("% s/n", Buf );

Result: 123456

2. Take a string of the specified length. In the following example, a string with a maximum length of 4 bytes is obtained.

Sscanf ("123456", "% 4 s", Buf );

Printf ("% s/n", Buf );

Result: 1234

3. Obtain the string of the specified character. For example, in the following example, the string is obtained when a space is encountered.

Sscanf ("123456 abcdedf", "% [^]", Buf );

Printf ("% s/n", Buf );

Result: 123456

4. Take a string that only contains the specified character set. For example, in the following example, take a string that only contains 1 to 9 letters and lowercase letters.

Sscanf ("123456 abcdedfbcdef", "% [1-9a-z]", Buf );

Printf ("% s/n", Buf );

Result: 123456 abcdedf

5. Obtain the string of the specified character set. For example, in the following example, a string with uppercase letters is used.

Sscanf ("123456 abcdedfbcdef", "% [^ A-Z]", Buf );

Printf ("% s/n", Buf );

Result: 123456 abcdedf

6. Given a string iios/12ddwdff @ 122, get the string between/and @ and filter out "iios/" first, then, send a string of content other than '@' to the Buf.

Sscanf ("iios/12ddwdff @ 122", "% * [^/]/% [^ @]", Buf );

Printf ("% s/n", Buf );

Result: 12 ddwdff.

7. Given a string "Hello, world", only world is retained. (Note: There is a space after)

Sscanf ("Hello, world", "% * S % s", Buf );

Printf ("% s/n", Buf );

Result: World

% * S indicates that the first matching % s is filtered out, that is, hello is filtered out.

If there is no space, the result is null.

Sscanf is similar to a regular expression, but does not have a strong regular expression. Therefore, we recommend that you use a regular expression for complex string processing.

//-------------------------------------------------------

Sscanf, indicating formatting input from string

In STR, input a number to X, which is 32700.

A long time ago, I thought c didn't have its own split string function. Later I found sscanf. For a long time, I thought sscanf could only define strings with spaces. Now I found that I was wrong.

Sscanf is a runtime function. Its prototype is simple:

Int sscanf (

Const char * buffer,

Const char * Format [,

Argument]...

);

Its powerful functions are reflected in its support for format.

I used to separate a string like this 2006: 03: 18:

Int A, B, C;

Sscanf ("200:0:18", "% d: % d", A, B, C );

And-2006: 04: 18:

Char sztime1 [16] = "", sztime2 [16] = "";

Sscanf ("2006:0:18-2006:04:18", "% s-% s", sztime1, sztime2 );

But later, I needed to handle

The space on both sides of '-' is canceled, but the % s definition of the string is broken.

I need to re-design a function to handle this situation? This is not complicated, but in order to make all the Code have a uniform style, I need to change many places and replace the existing sscanf with my own split function. I thought I must do this and fell asleep with a strong dissatisfaction with sscanf. I woke up and found that I didn't have.

The format-type has a type field such as %. If the string to be read is not separated by spaces, you can use % [].

% [] Is similar to a regular expression. [A-Z] indicates that all characters of A-Z are read, and [^ A-Z] indicates that all characters except a-Z are read.

That's why the problem was solved:

Sscanf ("2006:0:18-2006:04:18", "% [0-9,:]-% [0-9,:]", sztime1, sztime2 );