24. printf is cross-platform. The data type and output type must match.

1. Using printf should be said to be type insecure. Therefore, the stream input and output of C ++ is introduced.

For example:

# Include "stdint. H"

# Include "iostream"

Using namespace STD;

Int main ()

{

Int64_t A = 1;

Int B = 2;

Uint32_t uin = 1;

printf (" % P \ n ", & A, & B);

printf (" % LlU \ n ", uin);

cout

Printf ("% d \ n", a, B );

Return 0;

}

The output is:

0xbfd831e0 0xbfd831dc

13823853877176303617 // Error

1 2

1 0 // Error

As you can see,Uint32_tType. When LLD is used, an error occurs,Because printf reads data from the starting address offset byte Based on the type.

Using the stream in C ++ will not cause this problem. Attention should be paid to cross-platform applications.

2. type and number of bytes [3]

% Ld: Long int, 32-bit Platform 4 bytes

% LLD: long int, 32-bit platform 8 bytes

% Lf: double

**************

Typedef signed Char int8_t

Typedef short int int16_t;

Typedef int int32_t;

# If _ wordsize = 64

Typedef long int int64_t;

# Else

_ Extension __

Typedef long int int64_t;

# Endif

Refer:

[1]Http://www.vimer.cn/2011/08/printf-%E5%B0%8F%E4%BB%A3%E7%A0%81%EF%BC%8C%E5%A4%A7%E9%97% AE %E9%A2%98.html

[2]Http://www.cppblog.com/Solstice/archive/2010/04/06/111788.aspx

[3] type and number of bytes

Http://blog.sina.com.cn/s/blog_4b9eab320100sdex.html

[4] exploration of printf implementation

Http://www.cnblogs.com/hnrainll/archive/2011/08/05/2128496.html