将句子中的第一个字符转换为大写的程序

编写一个Java程序将句子中的第一个字符转换为大写，如果除了第一个字符之外，如果任何其他字符为大写，则转换为小写？

例子：

Input : gEEKs
Output :Geeks

Input :GFG
Output :Gfg


Input : GeeksforGeeks
Output : Geeksforgeeks

方法一：

C++

// C++ program to convert
// first character uppercase
// in a sentence
#include
using namespace std;
string convert(string str)
{
  for (int i = 0;
           i < str.length(); i++)
  {
    // If first character of a
    // word is found
    if (i == 0 && str[i] != ' ' ||
        str[i] != ' ' && str[i - 1] == ' ')
    {
      // If it is in lower-case
      if (str[i] >= 'a' && str[i] <= 'z')
      {
        // Convert into Upper-case
        str[i] = (char)(str[i] - 'a' + 'A');
      }
    }
 
    // If apart from first character
    // Any one is in Upper-case
    else if (str[i] >= 'A' &&
             str[i] <= 'Z')
 
      // Convert into Lower-Case
      str[i] = (char)(str[i] + 'a' - 'A');
  }
 
  return str;
}
 
// Driver code
int main()
{
  string str = "gEEks fOr GeeKs";
  cout << (convert(str));
  return 0;
}
 
// This code is contributed by Chitranayal

Java

// Java program to convert first character
// uppercase in a sentence
class GFG {
 
    static String convert(String str)
    {
 
        // Create a char array of given String
        char ch[] = str.toCharArray();
        for (int i = 0; i < str.length(); i++) {
 
            // If first character of a word is found
            if (i == 0 && ch[i] != ' ' ||
                ch[i] != ' ' && ch[i - 1] == ' ') {
 
                // If it is in lower-case
                if (ch[i] >= 'a' && ch[i] <= 'z') {
 
                    // Convert into Upper-case
                    ch[i] = (char)(ch[i] - 'a' + 'A');
                }
            }
 
            // If apart from first character
            // Any one is in Upper-case
            else if (ch[i] >= 'A' && ch[i] <= 'Z')
 
                // Convert into Lower-Case
                ch[i] = (char)(ch[i] + 'a' - 'A');           
        }
 
        // Convert the char array to equivalent String
        String st = new String(ch);
        return st;
    }
 
    public static void main(String[] args)
    {
        String str = "gEEks fOr GeeKs";
        System.out.println(convert(str));
    }
}

Python3

# Python3 program to convert first character
# uppercase in a sentence
def convert(s):
     
    # Create a char array of
    # given string
    ch = list(s)
     
    for i in range(len(s)):
  
        # If first character of a word is found
        if (i == 0 and ch[i] != ' ' or
                       ch[i] != ' ' and
                       ch[i - 1] == ' '):
  
            # If it is in lower-case
            if (ch[i] >= 'a' and ch[i] <= 'z'):
  
                # Convert into Upper-case
                ch[i] = chr(ord(ch[i]) - ord('a') +
                            ord('A'))
  
        # If apart from first character
        # Any one is in Upper-case
        elif (ch[i] >= 'A' and ch[i] <= 'Z'):
  
            # Convert into Lower-Case
            ch[i] = chr(ord(ch[i]) + ord('a') -
                        ord('A'))
     
    # Convert the char array
    # to equivalent string
    st = "".join(ch)
         
    return st;
 
# Driver code   
if __name__=="__main__":
     
    s = "gEEks fOr GeeKs"
     
    print(convert(s));
  
# This code is contributed by rutvik_56

C#

// C# program to convert first character
// uppercase in a sentence
using System;
 
class GFG {
     
    static String convert(String str)
    {
 
        // Create a char array of
        // given String
        char []ch = str.ToCharArray();
         
        for (int i = 0; i < str.Length; i++)
        {
 
            // If first character of a
            // word is found
            if (i == 0 && ch[i] != ' ' ||
                ch[i] != ' ' && ch[i - 1] == ' ')
            {
 
                // If it is in lower-case
                if (ch[i] >= 'a' && ch[i] <= 'z')
                {
 
                    // Convert into Upper-case
                    ch[i] = (char)(ch[i] - 'a' + 'A');
                }
            }
 
            // If apart from first character
            // Any one is in Upper-case
            else if (ch[i] >= 'A' && ch[i] <= 'Z')
 
                // Convert into Lower-Case
                ch[i] = (char)(ch[i] + 'a' - 'A');        
        }
 
        // Convert the char array to
        // equivalent String
        String st = new String(ch);
         
        return st;
    }
 
    // Driver code
    public static void Main()
    {
        String str = "gEEks fOr GeeKs";
        Console.Write(convert(str));
    }
}
 
// This code is contributed by Nitin Mittal.

Javascript

Java

// Java Program to capitalize each word in a string
public class GFG {
 
    // Method to convert the string
    static String capitailizeWord(String str) {
        StringBuffer s = new StringBuffer();
 
        // Declare a character of space
        // To identify that the next character is the starting
        // of a new word
        char ch = ' ';
        for (int i = 0; i < str.length(); i++) {
             
            // If previous character is space and current
            // character is not space then it shows that
            // current letter is the starting of the word
            if (ch == ' ' && str.charAt(i) != ' ')
                s.append(Character.toUpperCase(str.charAt(i)));
            else
                s.append(str.charAt(i));
            ch = str.charAt(i);
        }
 
        // Return the string with trimming
        return s.toString().trim();
    }
 
    // Driver Code
    public static void main(String args[]) {
 
        // Declare the string
        String s1 = "gEEks fOr GeeKs";
 
        // Convert that string into lowercase
        s1 = s1.toLowerCase();
 
        // Call the method to capitalize each word
        System.out.println(capitailizeWord(s1));
    }
}

Python3

# Python program to capitalize the
# first character of each word in a sentence
 
# Function definition
def solve (st):
    ascii_array = []
     
    # creating a list of ascii values
    # of all the characters in the sentence
    for i in range (0, len (st)):
        ascii_array.append (ord (st[i]))
     
    # check if the first character of
    # each word is a lowercase character.
    # To convert a lowercase character to an
    # uppercase character, we subtract 32 from
    # the ASCII value of lowercase character.
    if ascii_array[0] >= 97 and ascii_array[0] <= 122 :
        ascii_array[0] = ascii_array[0] - 32
     
    # create an empty list which will store
    # the characters corresponding to the
    # ascii values in ascii_array
    newlist = []
    newlist.append (chr (ascii_array[0]))
    for i in range (1, len (ascii_array)):
         
        # 32 is the ascii value for 'space' or ' '.
        # so we use this condition to check for
        # the next word in the sentence
        # as in a sentence we have space separated words
        if ascii_array[i] == 32:
            if ascii_array[i + 1] >= 97 and ascii_array[i+1] <= 122:
                ascii_array[i + 1] = ascii_array[i+1] - 32
        newlist.append (chr (ascii_array[i]))
         
    # in the end, we return a string after
    # joining the values obtained in newlist
    return (''.join (newlist))
 
# Driver Code
string = 'geeks for geeks'
result = solve (string)
print (result)
# This code is contributed by Kishan Mishra

输出：

Geeks For Geeks

方法 2：使用Java内置方法
要将每个单词大写，请调用 toLowerCase() 方法将字符串设为小写格式。迭代字符串，如果在前一次迭代中找到任何空格并且当前元素不是空格，则调用 toUpperCase() 方法将单词的第一个字母以大写格式并将字符串附加到缓冲区中。

下面是实现：

Java

// Java Program to capitalize each word in a string
public class GFG {
 
    // Method to convert the string
    static String capitailizeWord(String str) {
        StringBuffer s = new StringBuffer();
 
        // Declare a character of space
        // To identify that the next character is the starting
        // of a new word
        char ch = ' ';
        for (int i = 0; i < str.length(); i++) {
             
            // If previous character is space and current
            // character is not space then it shows that
            // current letter is the starting of the word
            if (ch == ' ' && str.charAt(i) != ' ')
                s.append(Character.toUpperCase(str.charAt(i)));
            else
                s.append(str.charAt(i));
            ch = str.charAt(i);
        }
 
        // Return the string with trimming
        return s.toString().trim();
    }
 
    // Driver Code
    public static void main(String args[]) {
 
        // Declare the string
        String s1 = "gEEks fOr GeeKs";
 
        // Convert that string into lowercase
        s1 = s1.toLowerCase();
 
        // Call the method to capitalize each word
        System.out.println(capitailizeWord(s1));
    }
}

方法3：使用Python3

方法：我们可以创建一个句子中所有单词的列表（比如 string_array）。创建 string_array 后，如果我们直接在该列表上工作并尝试更改单词的小写开头字符，我们将得到一个错误“ 'str' object does not support item assignment ”。为了避免这种情况，我们可以创建与 string_array 中的字符相对应的字符的 ASCII 值列表（比如 ascii_array）。

我们可以轻松地处理 ascii_array 并将单词的起始小写字符转换为大写，只需从它们的 ASCII 值中减去 32。更改 ascii_array 中的值后，我们使用chr()函数将 ascii_array 中的每个 ASCII 值转换为其对应的字符。 chr()函数返回与传入参数的 ASCII 值对应的字符。这样我们将获得一个大写字符串列表。

下面是上述方法的实现

Python3

# Python program to capitalize the
# first character of each word in a sentence
 
# Function definition
def solve (st):
    ascii_array = []
     
    # creating a list of ascii values
    # of all the characters in the sentence
    for i in range (0, len (st)):
        ascii_array.append (ord (st[i]))
     
    # check if the first character of
    # each word is a lowercase character.
    # To convert a lowercase character to an
    # uppercase character, we subtract 32 from
    # the ASCII value of lowercase character.
    if ascii_array[0] >= 97 and ascii_array[0] <= 122 :
        ascii_array[0] = ascii_array[0] - 32
     
    # create an empty list which will store
    # the characters corresponding to the
    # ascii values in ascii_array
    newlist = []
    newlist.append (chr (ascii_array[0]))
    for i in range (1, len (ascii_array)):
         
        # 32 is the ascii value for 'space' or ' '.
        # so we use this condition to check for
        # the next word in the sentence
        # as in a sentence we have space separated words
        if ascii_array[i] == 32:
            if ascii_array[i + 1] >= 97 and ascii_array[i+1] <= 122:
                ascii_array[i + 1] = ascii_array[i+1] - 32
        newlist.append (chr (ascii_array[i]))
         
    # in the end, we return a string after
    # joining the values obtained in newlist
    return (''.join (newlist))
 
# Driver Code
string = 'geeks for geeks'
result = solve (string)
print (result)
# This code is contributed by Kishan Mishra

输出：

Geeks For Geeks