我将两个c字符串(一个包含字符,另一个空为空)传递给一个函数,该函数应该包含包含字符的c-string,并使用从后面读取的字符串填充空c-string。操作简单,但不起作用。我无法弄清楚我做错了什么。
#include <iostream>
#include <cstring>
using namespace std;
void magic(char*, const char*, int);
int main()
{
char string1[20];
char string2[] = "This is a test";
char *str1 = string1;
char *str2 = string2;
int stringsize = strlen(string2);
magic(str1, str2, stringsize);
return 0;
}
void magic(char* string1, const char* string2, int stringsize)
{
cout << string2 << endl; //here it prints as expected
*(string1 + stringsize) = '\0';
string1 = string1 + stringsize - 1;
for(;*string2 != '\0' ;string1--, string2++)
{
*string1 = *string2;
}
cout << string1 << endl; //blank space is printed - expected "This is a test" reversed
cout << string2 << endl; //blank space is printed - expected "This is a test"
}
答案 0 :(得分:1)
如果您使用非常简单的字符串执行for
循环中的步骤,则可以在逻辑中看到问题。让我们说吧,
string1 = "This";
在循环的第一次迭代中,
string1 = "This";
string2 = "T";
在循环的第二次迭代中,
string1 = "his";
string2 = "hT";
在循环的第三次迭代中,
string1 = "is";
string2 = "ihT";
在循环的第四次迭代中,
string1 = "s";
string2 = "sihT";
在循环的第五次迭代中,
string1 = "";
string2 = "?sihT"; // You go past the start of the array.
因此,在for
循环结束后,您需要递增string2
以确保它指向数组的开头。
void magic(char* string1, const char* string2, int stringsize)
{
cout << string2 << endl;
*(string1 + stringsize) = '\0';
string1 = string1 + stringsize-1;
for(;*string2 != '\0' ;string1--, string2++)
{
*string1 = *string2;
}
// Add this.
string1++;
cout << string1 << endl; // This is now the reversed string.
cout << string2 << endl; // This is now the empty string since
// you kept incrementing it in the for
// loop until you reached the end of the
// string.
}