l What is the result of adding two character variables?

INT type. ANSI ISO C stipulates that two types narrower than int will be automatically promoted to int type before addition, subtraction, multiplication and division, or "bit and" and "bit or" operations, and the result of the operation is int type. So, let's say.

unsigned char a = 255, b = 1, c = 0;

Then, a+b == c is not true, because a+b == c is written as equivalent to (int)a + int)b == c.

a+b == 256 is true.

INT type. Because c stipulates that char data must be converted to int during operation.

INT type.

The following procedure can be used to verify this.

#include

int main()

char a=5,b=10;

return 0;

Broad byte is the use of two bytes to represent a Chinese character or character.

wchar_t wch = l"abc";wch is just an array of broad bytes, l"abc", which is the wide-byte constant, due to"abc", not a wide byte, adding l in front makes it a wide byte constant, you can see that l is actually a macro.

Once you understand the concept of constants, you can understand character constants and string constants, both of which are obviously constants. Then they are all of the same nature as the above a. The difference is that the data type is different.

A character constant is a constant of the data type char, and a string constant is a constant of the data type of a char string. For example: const char a ='a';

const char b = "hello world!";Here a is the character constant and b is the string constant.

The constant identifier is naturally the two identifiers A and B above.

Constant identifiers, like a and b above.

As for the symbolic constant, it should be the full name of the constant.

It is important to know the method of CONST and the essence of constants.

These are the format symbols used in C to format input and output. where %u is miswritten, but it is actually %u.

Formatting output functions include printf, fprintf, sprintf, etc.

Formatting input functions include scanf, fscanf, sscanf, etc.

This kind of function has a parameter for format str when entering and out, which introduces the format of the input and output strings, and when you need to input and output variable values, you need to replace them with the corresponding formatting characters.

The three formats mentioned in the title correspond to:

LD corresponds to the long type, that is, the long integer type.

d corresponds to the int type, that is, the integer type.

u corresponds to the unsigned int type, that is, the unsigned integer.

In addition, there are the following common types.

HD corresponds to the short type, that is, the short integer type.

hu corresponds to the unsigned short type, that is, the unsigned short integer.

f corresponds to the float type, that is, the single-precision floating-point type.

lf corresponds to the double type, that is, the double-precision floating-point type.

c corresponds to the char type, that is, the character type.

s corresponds to the char * type, which is a character pointer and an array of characters (both can be called strings).

X corresponds to the int type, but in 16 base input and output.

lx corresponds to the long type, which is also in hexadecimal form.

Here's a simple example:

#include

int main()

If you enter 1 2 3

will output i = 1

l = 2u = 3

The printf() function is a formatted output function, which is generally used to output information to a standard output device in a specified format. The printf() function is called in the following format: printf("Formatting Strings", Parametric Table).

Format output, which is a function in C that produces formatted output (defined in ). Used to output characters to terminals (monitors, consoles, etc.). Format control consists of text to be output and a description of the data format.

In addition to letters, numbers, spaces, and some numeric symbols, the text to be output can also use some escape characters to express special meanings.

d Signed 10 decimal integer (%ld long integer, %hd short integer) %hu unsigned short integer (%u unsigned integer, %lu unsigned long integer) %i signed decimal integer (%i and %d are no different, %i is the old-fashioned way of writing, both are in integer format).

o Unsigned occimal integer.

u Unsigned decimal integer.

x is an unsigned hexadecimal number with a lowercase abcdef for %x unsigned hexadecimal digits and an uppercase abcdef for %f inputs and outputs as floating-point (%lf double-precision floating-point)%e e floating-point numbers in scientific representation format.

c The input and output are single characters.

s input and output as strings.

Variable format. For example, printf("%d",a);The east in double quotation marks is determined by the type of the variable that follows, %ld if a is long, and %f if float

Those are format placeholders: %id placeholders for displaying long integer data on the screen, %d placeholders for displaying basic integer data on the screen, %u placeholders for displaying unsigned integer data on the screen, %c placeholders for displaying character data on the screen, %f placeholders for displaying floating-point data on the screen, %s placeholders for displaying string data on the screen.

%ld, %d, and %u represent the types of output data formats, which are long integer integer and unsigned integer.

An L in front of a string indicates that the string is a Unicode string.

t is a macro that automatically precedes the string if the project uses the unicode character set (unicode macro is defined), otherwise the string remains unchanged. So, visual

When defining strings in C++, use t to ensure compatibility. VC supports ASCII and Unicode character types, and using T can ensure that the program does not need to be modified when converting from ASCII encoding to Unicode encoding type.

Therefore, when you write C++ (MFC program) under VS2005 vs2008, it is better to use T; And in VS2010 and so on, just use L!

l"hello, world"This string is stored in wchar.

t"hello, world"If the project defines unicde, the string is saved as wchar, and if it is not defined, it is saved as char.

2. L is liter, and L here is the unit of volume liters. Refers to the exhaust volume of a car's engine. This means that this engine has a liter of displacement. There is no T behind the displacement, and the L is generally a naturally aspirated engine.

3. T stands for the abbreviation of turbocharging (turbo), if you see turbo or T at the rear of the car, it means that the engine used in the car is a turbocharged engine.

The requirements of the problem are different from the standard library function strcmp, which requires s1 >s2 to return -1, s1*str2).

return -1;

str1++;

str2++;

if(str1==null)

return 1;

if(str2==null)

return -1;

return 0;

size_t mbstowcs( wchar_t *wcstr, const char *mbstr, size_t count );

Use this function, or use multibytetowidechar

Hello, maybe you are going to take C language level 2 and are doing the question. I can see at once that you are receiving the value of l There is a problem there, and it should be written as ".scanf("%d",&l);But I wrote it down and ran it for you.

Correct** as follows, you just need to change the double quotation marks on line 18 there:

#include

void main()

Running results;

A character variable can be assigned as an integer, which represents the character that the number corresponds to in the ASII lookup table.

helloworld"It's a string... Not characters.

Well, how to prove that he is also regular, first you have to choose his extreme number.

The fake l is a combination of each string reversed in the normal level lol.,If it turns out, I don't think this is something I don't understand yet.。

There are a lot of things that we should do with assumptions and formal things, and very well.

Assuming that it is a set of normals and each string in L4L after reversal, how to prove that it is also normal. I'm sorry for this, I don't know to do sorry.

Use the original tutoring homework to help you search for it.

Get to the regular machine early. I can follow along with anything I have to explain.