Procedural APE's---C language detail (C language Boolean type, continue details, sizeof example, strlen example)

Main contents: Boolean type, continue detail, sizeof example, strlen example in C language
One, Boolean type

Maybe a lot of people don't know that now C has a Boolean type: Starting with the C99 standard, the type name is "_bool"

Before the C99 standard we used to imitate the definition of Boolean type, common in the following ways:

1, the way one

#define TURE 1#define FALSE 0

2, Mode two

typedef enum {false, true} bool;

3, Mode three

typedef int BOOL

idle int wastes memory and is used by memory-sensitive programs

typedef char BOOL

The bool type is introduced in the new header file in the C99 standard and is compatible with bool in C + +. The header file is Stdbool.h, and its source code is as follows:

#ifndef _stdbool_h #define _STDBOOL_H  #ifndef __cplusplus  #define BOOL    _bool #define TRUE    1 #define False   0  #else/* __cplusplus */  * supporting <stdbool.h> in C + + is a GCC extension.  */#define _BOOL   BOOL #define BOOL    BOOL #define FALSE   False #define TRUE    true #endif/  * __ Cplusplus */* Signal and all the  definitions is present.  

Second, continue

Continue details are to be used in the loop, or it will be an error

#include <stdio.h>int main () {int a = 1;switch (a) {case 1:printf ("1\n"); continue;//continue must be used to break in the loop  ; Case 2:printf ("2\n");d Efault:break;} return 0;}

Iii. Examples of sizeof

#include <stdio.h> int b[100];void fun (int. b[100]) {printf ("in fun sizeof (b) =%d\n", sizeof (b));//sensory function The array is handled by the pointer}in T Main () {char *p = null;printf ("sizeof (P) =%d\n", sizeof (p));p rintf ("sizeof (*p) =%d\n", sizeof (*P));p rintf ("---------- -------------\ n "), char a[100];p rintf (" sizeof (a) =%d\n ", sizeof (a));p rintf (" sizeof (a[100]) =%d\n ", sizeof (a[100])); printf ("sizeof (&a) =%d\n", sizeof (&a));p rintf ("sizeof (&a[0]) =%d\n", sizeof (&a[0]));p rintf ("------ -----------------\ n "); fun (b); return 0;}

Output:

Iv. Examples of strlen

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdbool.h>/* questions 1, 0 and + 0 How to store 2, int i = -20 in memory respectively;   unsigned j = ten;   What is the value of i+j? Why? 3. What's wrong with the following code? unsigned i;for (i = 9; i>=0; i--) {printf ("%u\n", I);} */int Main () {bool bool2 = 0;  /* C language Bool type is only in C99, if not include header file stdbool.h, directly with Bool will report error */_bool bool1 = 1; /* Direct use of _bool does not include Stdbool.h*/char a[280];char *str = "12340987\0"; char test[] = "12340987"; int i;printf ("strlen (a) =%d \ n ", strlen (a)); for (i = 0; i < 280; i++) {a[i] = -1-i;//a[256]  = 0//printf (" a[%d] =%d\n ", I,a[i]);} printf ("strlen (a) =%d\n", strlen (a));  Why is 255 printf ("strlen (str) =%d\n", strlen (str));p rintf ("strlen (test) =%d\n", strlen (test)); char s = ' rintf ';p "\ \ 0 =%d\n ", s); return 0;}

Output:

Procedural APE's---C language detail (C language Boolean type, continue details, sizeof example, strlen example)