The fourth day of C language learning 2

Shows the precision of float and double , precision: Refers to the precise degree of the numeric value, floating-point type can represent a large range of values, but only a few are accurate, you can pass the small

The number of digits to be taken, float The number of decimal parts can have up to 7 is a valid number, but it is absolutely guaranteed to be 6 bit, Double The number of small parts is divided into - a valid number, but absolutely guaranteed.

is a the bit

#include <stdio.h>

int main ()

{

Double x=3.0123456789111118;

printf ("%f\n", X);

return 0;

}

The default %f only outputs six digits after the decimal point, to specify how many bits to output need to use the following format

printf ("%.16f\n", X);

#include <stdio.h>

int main ()

{

Double x=3.0123456789111118;

printf ("%a\n", X);

return 0;

}

%A Converts the value of x to a hexadecimal floating-point number,%e is exponential,and%f is in decimal form, and the compiler defaults to seeing the floating-point numbers as Double type

#include <stdio.h>

int main ()

{

Char ch;

ch=97;

printf ("ch:%c\n", ch);

return 0;

}

Char CH, the system allocates a byte space for the variable and places a label ch on that memory space , and%c represents the character type

#include <stdio.h>

int main ()

{

Char ch;

Ch= ' a ';

printf ("ch:%c\n", ch);

printf ("ch:%d\n", (int) ch);

return 0;

}

printf ("ch:%d\n", (int) ch); the role of the output variable CH corresponding to the ASSIIC code value, (int) in the () is a forced type conversion operator, and an int in() represents the type to convert to

A character variable can only hold one character, "' contains a character," "contains a string of characters, so the above ch=' a '; cannot be written ch="a";

#include <stdio.h>

int main ()

{

int i;

for (i=32;i<127;i++)

{

printf ("%c\n", (char) i);

}

return 0;

}

The above program is to output the characters corresponding to the 32~126 ASCII code in turn

#include <stdio.h>

int main ()

{

Char ch1=0;

Char ch2= ' 0 ';

printf ("%d\n%d\n", (int) ch1, (int) CH2);

return 0;

}

Run the above program can get the number 0 corresponding to the ASIIC code of 0, and the character 0 corresponds to the ASIIC Code is

#include <stdio.h>

int main ()

{

float f=3.1415f;

int a=f;

printf ("%d\n", a);

printf ("%f\n", f);

return 0;

}

int a=f; will be F Copy, assign the copied value to the value of the a , so F the value of itself does not change, the format character %f Default Output 6 decimal Places

Signed or unsigned char and short in an expression are automatically converted to int, as illustrated below:

#include <stdio.h>

int main ()

{

Char c1=12,c2=108;

printf ("%d\n", C1+C2);

return 0;

}

and c2 int c1 and c2

when passed as a parameter to the function Char and the Short type will be promoted to int type, float the type will be promoted to Double type, for example:

#include <stdio.h>

int main ()

{

Char ch= ' a ';

printf ("Ch saved ASCII code value:%d\n", ch);

return 0;

}

Ch is automatically converted to int type, so no casting is necessary

The fourth day of C language learning 2