我的程序出现问题。我几乎已经完成了它,但最终结果并没有成功。我已经用两种方式编写了它,一种是带有switch语句,另一种是if else语句,但都没有正常工作。它们都为我编译并具有干净的构建但不会按预期运行。
#include <iostream>
#include <cstdio>
#include <iomanip>
using std::cout;
using std::cin;
using std::endl;
int main()
{
int i = 0;
const int size = 27;
char newline = '\n';
char *pnumber = 0;
int selection = 0;
cout << "PRINGING CONTENTS OF ARRAY" << endl;
cout << "====================================================" << endl;
char alphabet[size] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'
, 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y'
, 'Z' , 0 };
for (i = 0; i < size; i++)
{
cout << alphabet[i] << " ";
}
cout << newline;
cout << newline;
cout << "This is the title to your Program related to the alphabet."
<< endl;
cout << endl;
cout << "Select the index that coincides with the alphabet." << endl;
cout << "For example, the number 7 should display the letter G" << endl;
cout << endl;
cout << "Enter an index between 1 and 26: ";
cin >> i;
cout << "The number you selected: " << i;
cout << newline;
cout << "The letter at this index: " << alphabet[i - 1];
cout << endl;
cout << newline;
cout << newline;
cout << "PRINTING CONTENTS OF ARRAY and adding x to every other element" << endl;
pnumber = &alphabet[1];
for (i = 0; i < size; i += 1)
{
if (i % 2 == 0)
{
cout << alphabet[i] << " ";
}
else
{
cout << "x ";
}
}
cout << newline;
cout << newline;
cout << "PRINTING CONTENTS OF ARRAY USING THE MOD Option" << endl;
cout << "=========================================================" << endl;
cout << "Do you want the letters of the alphabet starting from index 0, A, or index 1, B: ";
cin >> selection;
switch (selection)
{
case 0:
{
for (i = 0; i < size; i += 2)
{
cout << "Even Numbered Elements=" << i << " ";
cout << "Contents of Element within Array is=" << alphabet[i];
break;
}
}
case 1:
{
for (i = 1; i < size; i += 2)
{
cout << "Odd Numbered Elements=" << i << " ";
cout << "Contents of Element within Array is=" << alphabet[i] << endl;
break;
}
}
default: cout << "You entered an invalid esponse.";
}
cout << endl;
return 0;
} //End of Int Main
使用if else完成的最后一部分是:
cout << newline;
cout << newline;
cout << "PRINTING CONTENTS OF ARRAY USING THE MOD Option" << endl;
cout << "=========================================================" << endl;
cout << "Do you want the letters of the alphabet starting from index 0, A, or index 1, B: ";
cin >> selection;
if (selection = 0){
for (i = 0; i < size; i += 2)
{
cout << "Even Numbered Elements=" << i << " ";
cout << "Contents of Element within Array is=" << alphabet[i] << endl;
}
}
else{
for (i = 1; i < size; i += 2)
{
cout << "Odd Numbered Elements=" << i << " ";
cout << "Contents of Element within Array is=" << alphabet[i] << endl;
}
}
return 0;
} //End of Int Main
1)第一部分输出字母,2)接下来它提示输入一个数字并且应该给出相关字母,3)接下来程序应该输出,其他每个字母都是x,例如A x C x E x ........ 4)最后它应该提示用户选择o在A或1处开始字母表并从B开始,然后它将输出每隔一个字母。最后一部分不起作用。它没有给出选项,而是每次都做同样的事情。我已经通过其他方式进行了调整,而且两次都会做一个或另一个。我究竟做错了什么?
答案 0 :(得分:5)
第二部分改变
if (selection = 0){
到
if (selection == 0){
表达式selection = 0
是一项作业,但您需要进行比较。
此外,为了检查均匀度,您可以使用%
运算符。 E.g:
if (selection % 2 == 0)
{
// if even
}
else
{
// if odd
}
修改强>
为了避免将来出现这种错误,请自己在比较运算符的左侧写一个常量值,例如
if (0 == selection)
如果你错误的编译器将显示关于l值的错误,那么mast就是变量。
编辑2(关于开关和for):
在以下代码中
switch (selection)
{
case 0:
{
for (i = 0; i < size; i += 2)
{
cout << i << " ";
break;
}
}
case 1:
...
}
break
语句是指for
,而不是switch
,因此:
1)for
只会被执行一次;
2)selection
0
case 1
无论如何都会在case 0
之后工作。
正确的代码必须如下
switch (selection)
{
case 0:
{
for (i = 0; i < size; i += 2)
{
cout << i << " ";
}
break;
}
case 1:
...
}
答案 1 :(得分:0)
请进行更改#
if (selection == 0)
我认为上述变化可以解决问题。在您的代码中,您不是在比较,而是在其中分配0,因此如果执行并且如果不是标准,则永远不会希望进行分配。
希望这会有所帮助。