What data type is char?

Char is one of the weirder C/C integer data types. Others such as int/long/short, etc. default to signed when signed/unsigned is not specified. However, char is not specified as signed/unsigned in the standard. Compilation The compiler can be implemented as signed or unsigned. Some compilers, such as the pSOS compiler, can also specify whether it is a signed or unsigned number through a compilation switch.

Data type

Definition: Can be used in computer programming languages ​​(c, c, java, VFP,, pascal, etc.) A basic data type that holds a single character.

In C/C, char is one of the weirder C/C integer data types, and there is a special language about char which is char *, which has special semantics in C/C. It is different from signed char * and unsigned char *. It is specifically used to refer to strings ending with '\0'

In C, you can try it with

char *p="abcd";

can be compiled

, but if you use

signed char *p="abcd";

or

unsigned char *p="abcd";

, it will not be compiled.

These are clearly explained in the C/C language standard or some classic books such as TheC Programing Language.

Judge the default char symbol of the compiler

#include <stdio.h>
int main()
{
  char c=-1;
  if(c<200){
  printf("signed\n");
  }
  else{
  printf("unsigned\n");
  }
  return 0;
}
/*char 还在pascal语言中应用。在Pascal语言中，字符常量是由单个字符组成，所有字符采用ASCII编码也称ASCII码*/

Field type editing

In MYSQL, the field type char refers to : A string represented by a fixed length of a specified length; for example, char (8), the database will use a fixed 1 byte (eight bits) to store the data, and strings with less than 8 bits will be followed by null characters.

Character conversion

The char function in excel is used to return the character corresponding to the numeric code. Its usage: =char (number)

Among them, the parameter number is the converted character code, between 0 and 255. char occupies one byte, which is 8 binary bits, but it represents It is a signed type, so the represented range is -128~127; uchar represents an unsigned type, so the represented range is 0~255.

Algebraic concepts

Char is the abbreviation of characteristic, which represents the characteristics of a ring or domain, that is, the smallest non-negative integer n such that ne=0. (e is the unit element).

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