無法掌握簡單的布爾循環if/else program in C++

Question

我需要一些幫助，從C++任務中找出幾個部分。我被要求編寫一個程序如下：

編寫一個程序，接受來自鍵盤的輸入（輸入 按Enter鍵終止），並計算字母數（AZ和az），數字（ 0-9）和其他字符。使用cin輸入字符串並使用以下循環結構來檢查字符串中的每個字符，並使用「if」語句和多個「else if」語句。

char s[50]; 
int i; 

. . . 

i = 0; 
while (s[i] != 0) { // a string is terminated with a null (0) value 

. . . 

i++; 
} 

你的程序應該利用關係運算符（例如，== <> < => =！=），以確定一個特定的字符是否是字母，數字，或其他字符。您只可以#include和 不得使用任何其他包含文件。

程序應該有類似以下的輸出：

輸入字符的連續字符串沒有空格（例如：aBc1234!@#$%）

輸入您的字符串：aBc1234!@#$%

your string has 12 total characters 
3 letters 
4 numerical characters 
5 other characters 

下面是一個計算小寫字母的示例程序：

// PROG07.CPP example 

#include <iostream> 
using namespace std; 


int main() 
{ 
char s[50]; 
int i; 
int lowercase = 0; 

//get string from the user 
cout << "Enter a continuous string of characters with no blanspaces\n" 
cout << "(example: aBc1234!@#$%)" << endl << endl; 
cout << "Enter your string: "; 
cin >> s; 
cout << endl; 

// loop through the string, lower case letters 
// note, strings (character arrays) have an invisible 
// zero value at their end 
i = 0; 
while (s[i] != 0) // while the character does not have ASCII code zero 
{ 
if ((s[i] >= 'a' && s[i] <= 'z')) 
lowercase++; 
i++; 
} 

cout << "Your string has " << lowercase << " lower case letters" << endl; 

// including the next line for Dev-C++: 
system("pause"); // not needed for CodeBlocks 

return 0; 
} 

到目前爲止，我想出了這一點：

#include <iostream> 
using namespace std; 

int main() 
{ 
char s[50]; 
int i; 
int lowercase, uppercase, numChars, otherChars = 0; 

cout << "Enter a continuous string of characters" << endl; 
cout << "(example: aBc1234!@#$%)" << endl; 
cout << "Enter your string: "; 
cin >> s; 
cout << endl; 

while (s[i] != 0) // while the character does not have ASCII code zero 
{ 
if ((s[i] >= 'a' && s[i] <= 'z')) 
    lowercase++; 
    i++; 
} 
while (s[i] != 0) 
{ 
if ((s[i] >= 'A' && s[i] <= 'Z')) 
    uppercase++; 
    i++; 
} 
cout << lowercase + uppercase << " letters" << endl; 
i = 0; 
while (s[i] != 0) 
{ 
if ((s[i] >= '0' && s[i] <= '9')) 
    numChars++; 
    i++; 
} 

cout << numChars << " numerical characters" << endl; 

return 0; 
} 

任何幫助將不勝感激。

Answer 1

你有充分的循環之前爲0重置我到：

#include <iostream> 
using namespace std; 

int main() 
{ 
char s[50]; 
int i; 
int lowercase, uppercase, numChars, otherChars = 0; 

cout << "Enter a continuous string of characters" << endl; 
cout << "(example: aBc1234!@#$%)" << endl; 
cout << "Enter your string: "; 
cin >> s; 
cout << endl; 

i = 0; //missing 
while (s[i] != 0) // while the character does not have ASCII code zero 
{ 
if ((s[i] >= 'a' && s[i] <= 'z')) 
    lowercase++; 
    i++; 
} 
i = 0; // missing 
while (s[i] != 0) 
{ 
if ((s[i] >= 'A' && s[i] <= 'Z')) 
    uppercase++; 
    i++; 
} 
cout << lowercase + uppercase << " letters" << endl; 
i = 0; 
while (s[i] != 0) 
{ 
if ((s[i] >= '0' && s[i] <= '9')) 
    numChars++; 
    i++; 
} 

cout << numChars << " numerical characters" << endl; 

return 0; 
} 

Answer 2

看起來不錯，到目前爲止，僅有幾件事情

首先，你只需要一個while循環：

while (s[i] != 0) 
{ 
    //All your if checks can go in here 
} 

然後，根據您需要的輸出，您將需要4個變量：

int total, lettters, numbers, otherCharacters; 

在你的循環的開始，加總：

while (s[i] != 0) 
{ 
    total++; 
} 

然後，你將需要3，如果你的while循環，一個字母，一個數字，以及一個用於其他字符內檢查：

根據輸出

if ((s[i] > 'a' && s[i] < 'z') || (s[i] > 'A' && s[i] < 'Z')) { ... } 
else if (s[i] > '0' && s[i] < '9') { ... } 
else { ... } 

然後，只需輸出所有的變量，你提到的：

cout << "your string has " << total << " total characters, " << letters << " letters, " << numbers << " numerical characters, and " << otherCharacters << " characters.";