数组指针

#include 
#include 
int main()
{
    int a[3][2] = {{1,2},{3,4},{5,6}};
    int (*p)[2],i,j;
    p = a;
    for(i=0;i<3;i++)
    {
        for(j=0;j<2;j++)
        {
            printf("%d %d
",p[i][j],*(*(p+i)+j));
        }
        printf("
");
    }
    return 0;
}

10.7 字符指针和字符串

c语言通过使用字符数组来处理字符串
char类型的指针变量称为字符指针变量，字符指针变量与字符有着密切关系，他也被用来处理字符串
初始化字符指针是把内存中字符串的首地址赋予指针
当一个字符指针指向一个字符串常量时，不能修改指针指向的对象的值

#include 
#include 
int main()
{
    char ch1[] = "hello";
    char ch2[] = "hello";
    char *p;
    p = ch1;
    if(isalpha(*p))
    {
        if(isupper(*p))
        {
            *p = tolower(*p);
        }
        else
        {
            *p = toupper(*p);
        }
    }
    printf("%s %s
",p,ch1);
    p = ch2;
    printf("%s
",ch2);
    return 0;
}

静态存储区：
1、全局变量
2、static局部变量
3、字符串常量//char *p = “welcome”;
栈区：指针变量
字符串常量不能被修改，因为存储在静态存储区//会发生段错误

#include 
#include 
int main()
{
    char a[] = "hello";
    char *p = "world";
    strcpy(p,a);//段错误，字符串常量被赋值
    puts(a);
    puts(p);
    return 0;
}

#include 
#include //实现字符串连接功能
int main()
{
    char a[100] = "hello world";
    char *p = "welcome";
    int i = 0;
    char *q;
    q = p;
    while(*(a+i) != '
#include 
#include //实现字符串连接功能
int main()
{
char a[100] = "hello world";
char *p = "welcome";
int i = 0;
char *q;
q = p;
while(*(a+i) != '\0')
{
i++;
}
while(*p != '\0')
{
*(a+i) = *p;
p++;
i++;
}
*(a+i) = *p;
p = q;
puts(a);
puts(p);
return 0;
}
')
    {
        i++;
    }
    while(*p != '
#include 
#include //实现字符串连接功能
int main()
{
char a[100] = "hello world";
char *p = "welcome";
int i = 0;
char *q;
q = p;
while(*(a+i) != '\0')
{
i++;
}
while(*p != '\0')
{
*(a+i) = *p;
p++;
i++;
}
*(a+i) = *p;
p = q;
puts(a);
puts(p);
return 0;
}
')
    {
        *(a+i) = *p;
        p++;
        i++;
    }
    *(a+i) = *p;
    p = q;
    puts(a);
    puts(p);
    return 0;
}