【C语言指针】通过指针引用字符串 （代码）

//#include
//int main() {
// char a[] = “i am a student.”,b[20];
// int i=0;
// for (i = 0; *(a + i) != ‘’; i++)
// *(b + i) = *(a + i);
// *(b + i) = ‘’;//字符串结束标志，没有’’会出现乱码
// printf(“%sn”, a);
// printf(“%sn”, b);
// return 0;
//}

//用指针变量来处理复制
#include
int main(){
char a[] = “i am a boy.”;
char b[20],*p1,*p2;
p1 = a; p2 = b;
for (p1=a; p1 != “”; p1++, p2++)
*p2 = *p1;
*p2 = ‘’;
printf(“%sn”, a);
printf(“%sn”, b);
return 0;
}

//用字符数组名作函数参数
#include
void copy_string(char from[], char to[])
{
int i = 0;
while (from[i] != ‘’) {
to[i] = from[i]; i++;
}to[i] = ‘’;
}
int main() {
void copy_string(char from[], char to[]);
char a[] = “i am a student.”;
char b[] = “you are a good man!”;
printf(“a=%snb=%sn”,a, b);
printf(“n复制n”);
copy_string(a, b);
printf(“a=%snb=%sn”, a, b);
return 0;

}

//用字符指针型变量作实参
#include
void copy_string(char from[], char to[])
{
int i = 0;
while (from[i] != ‘’) {
to[i] = from[i]; i++;
}to[i] = ‘’;
}
int main() {
void copy_string(char from[], char to[]);
char a[] = “i am a student.”;
char b[] = “you are a good man!”;
char* from = a; char* to = b;
printf(“a=%snb=%sn”, a, b);
printf(“n复制n”);
copy_string(from,to); // 实参为字符指针型变量
printf(“a=%snb=%sn”, a, b);
return 0;

}

//用字符指针型变量作实参和形参
#include
void copy_string(char *from, char *to)
{
for (; from != ‘’; from++, to++) {
to = from;
}to = ‘’;
}
int main() {
void copy_string(char from, char to);
char a[] = “i am a student.”;
char b[] = “you are a good man!”;
char p = b; char q = a;`
printf(“a=%snb=%sn”, a, b);
printf(“n复制n”);
copy_string(q,p); // 实参为字符指针型变量
printf(“a=%snb=%sn”, a, b);
return 0;

}

**while(q++ = p++);
这一行代码可替代for语句三行代码：
int i=0;
for (i = 0; *(a + i) != ‘’; i++)
*(b + i) = *(a + i);
*(b + i) = ‘’;

#include
int main() {
	char a[] = "i am a student.",b[20]="you are a good man.";
	char* p = a; char* q = b;
	while(*q++ = *p++);
	printf("%sn", a);
	printf("%sn", b);
	return 0;
}
//注意：int i=0;
//for(*(a+i)++=*(b+i)++)这种写法不行，数组元素是常量，是不能进行++操作的
//想要数组位置向前或者向后，只能使用指针变量

//用字符指针型变量作实参和形参
#include
void copy_string(char* from, char* to)
{
	while (*to++ = *from++);//将*from赋给*to，如果赋值后的*to值等于''，则循环终止（''已赋值给*to)
}
int main() {
	void copy_string(char* from, char* to);
	char  a[] = "i am a student.";
	char b[] = "you are a good man!";
	char* p = b; char* q = a;
	printf("a=%snb=%sn", a, b);
	printf("n复制n");
	copy_string(q, p);  // 实参为字符指针型变量
	printf("a=%snb=%sn", a, b);
	return 0;


}