无法理解带有特殊字符的C ++字符串的输出
我正在使用带有特殊字符的c ++字符串来控制输出。大多数结果都可以预测，但其中一个结果超出了我的预期。我无法在任何地方找到答案。
平台：Windows 7企业版6.1（Build 7601：Service Pack 1）编译器：g ++（GCC）8.2.0，c ++ 17
#include <iostream>
int main(){
using namespace std;
char numString[12] = "0123456789\n";
//This is group 1
numString[3] = '\t';
numString[4] = '\b';
cout << "Group 1 output:\n" << numString << endl;
//This is group 2
numString[3] = '\b';
numString[4] = '\t';
cout << "Group 2 output:\n" << numString << endl;
//This is group 3
numString[3] = '\n';
numString[4] = '\b';
cout << "Group 3 output:\n" << numString << endl;
//This is group 4
numString[3] = '\b';
numString[4] = '\n';
cout << "Group 4 output:\n" << numString << endl;
//This is group 5
numString[2] = '\b';
numString[3] = '\b';
numString[4] = '\n';
cout << "Group 5 output:\n" << numString << endl;
return 0;
}
控制台中的输出：
第1组输出：
01256789
第2组输出：
01 56789
第3组输出：
012
56789
第4组输出：
012
56789
第5组输出：
01
56789
第四组产量预计为，
第4组输出：
01
56789
虽然输出实际上是，
第4组输出：
012
56789
我无法理解的是为什么角色'2'仍在那里。
有人可以帮我理解这个问题吗？谢谢。
在看到下面的答案，尤其是zar之后，我相信我已经理解了这个问题，并想在此总结一下。
- Windows cmd console is in non-destructive mode when no physical keystrokes detected.
- Any new output starts overwriting the existing ones from the current cursor. Sounds redundant but necessary. If there is any new character output, it will overwrite the existing one until new characters are used up. If there are still more existing characters left, they will continue existing over there and may look like "output" behind the new characters.
- '\b' only moves the cursor one character back. It does not delete anything.
- '\n' only moves the cursor to the next line. It does not move any character behind it to the next line.
- '\r' only moves the cursor to the beginning of the current line.
Please pay attention to move the cursor.
I'd like to paste all of the code here:
//strwithspecialchar.cpp -- Understand special characters in C++ string
#include <iostream>
int main(){
using namespace std;
char numString[12] = "0123456789\n";
//This is group 1
numString[3] = '\t';
numString[4] = '\b';
cout << "Group 1 output:\n" << numString << endl;
//This is group 2
numString[3] = '\b';
numString[4] = '\t';
cout << "Group 2 output:\n" << numString << endl;
//This is group 3
numString[3] = '\n';
numString[4] = '\b';
cout << "Group 3 output:\n" << numString << endl;
//This is group 4
numString[3] = '\b';
numString[4] = '\n';
cout << "Group 4 output:\n" << numString << endl;
//This is group 5
numString[2] = '\b';
numString[3] = '\b';
numString[4] = '\n';
cout << "Group 5 output:\n" << numString << endl;
//This is group 6
numString[2] = '\b';
numString[3] = '3';
numString[4] = '\n';
cout << "Group 6 output:\n" << numString << endl;
//This is group 7
numString[2] = '2';
numString[3] = '\b';
numString[4] = '\a';
cout << "Group 7 output:\n" << numString << endl;
//This is group 8
numString[3] = '\b';
numString[4] = '\r';
cout << "Group 8 output:\n" << numString << endl;
//This is group 9
numString[3] = '\b';
numString[4] = '\n';
numString[8] = '\r';
cout << "Group 9 output:\n" << numString << endl;
return 0;
}
And the output below for better understanding these special characters:
Group 1 output:
01256789
Group 2 output:
01 56789
Group 3 output:
012
56789
Group 4 output:
012
56789
Group 5 output:
01
56789
Group 6 output:
03
56789
Group 7 output:
0156789
Group 8 output:
56789
Group 9 output:
012
967
Stack Overflow用户
发布于 2019-06-14 13:14:10
控制台显示的是正确的输出，即
Group 4 output:
012
56789
你错了预料到
Group 4 output:
01
56789
什么\b性格确实是移动光标一个字符后面，它并没有将其删除。所以发生的事情是光标移回2但角色仍然存在。
012
^
下一个字符\n不是可打印字符而是控制字符，它只是将光标移动到下一行，因此它不会覆盖已打印的字符。
如果你这样做：
//This is group 4
numString[3] = '\b';
numString[4] = 'X';
cout << "Group 4 output:\n" << numString << endl;
现在\b移动到2但是下一个字符'X'立即覆盖它，产生如预期的以下结果。
Group 4 output:
01X56789
即使您添加另一个退格，另一个演示是：
numString[3] = '\b';
numString[4] = '\b';
numString[5] = '\n';
光标现在为1
012
^
Now it encounters the \n (new line) as next character and it simply moves the cursor to the next line so 1 and 2 are never overwritten as they were already printed and remains now in the previous line.
The output hence now is, as expected:
Group 4 output:
012
6789
https://stackoverflow.com/questions/-100009098
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