C 语言程序：替换字符串中字符的第一次出现

编写一个 C 语言程序，用示例替换字符串中的字符的第一次出现。

C 语言程序：替换字符串中字符的第一次出现 示例 1

此 C 程序允许用户输入一个字符串（或字符数组）和一个字符值。接下来，它将搜索并替换字符串中字符的第一次出现。

/* C Program to Replace First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch, Newch;
  	int i;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Replace :  ");
  	scanf("%c", &ch);
  	
  	getchar();
  	
  	printf("\n Please Enter the New Character :  ");
  	scanf("%c", &Newch);
  	
  	for(i = 0; str[i] != '\0'; i++)
  	{
  		if(str[i] == ch)  
		{
  			str[i] = Newch;
  			break;
 		}
	}
	printf("\n The Final String after Replacing First occurrence of '%c' with '%c' = %s ", ch, Newch, str);
	
  	return 0;
}

首先，我们使用For 循环来迭代字符串中的每个字符。

for(i = 0; i <= strlen(str); i++)
{
	if(str[i] == ch)  
	{
		str[i] = Newch;
		break;    	
	}
}

str[] = Hello World
ch = l
Newch = @

For 循环第一次迭代：for(i = 0; i <= strlen(str); i++)

在 C 语言的 While 循环中，我们使用If 语句来检查 str[0] 是否等于用户指定的字符。

if(str[i] == ch) => if(H == l)

上述条件为假。因此，i 将递增，Flag 仍为 0。

第二次迭代：for(i = 1; 1 <= 11; 1++)

if(str[i] == ch) => if(e == l) – 条件为假。因此，i 将递增，Flag 仍为 0。

第三次迭代：for(i = 2; 2 <= 11; 2++)
if(str[i] == ch) => if(l == l) – 条件为真
str[i] = Newch
str[2] = @
并且，break 语句将退出循环。

接下来，我们使用 printf 语句打印最终字符串。

printf("\n The Final String after Replacing First occurrence of '%c' with '%c' = %s ", ch, Newch, str);

C 语言程序：替换字符串中字符的第一次出现 示例 2

此程序替换第一个字符出现与上面相同。在这里，我们只是将 For 循环替换为While 循环。

/* C Program to Replace First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch, Newch;
  	int i = 0;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Replace :  ");
  	scanf("%c", &ch);
  	
  	getchar();
  	
  	printf("\n Please Enter the New Character :  ");
  	scanf("%c", &Newch);
  	
  	while(i <= strlen(str))
  	{
  		if(str[i] == ch)  
		{
  			str[i] = Newch;
  			break;
 		}
 		i++;
	}
	printf("\n The Final String after Replacing First occurrence of '%c' with '%c' = %s ", ch, Newch, str);
	
  	return 0;
}

 Please Enter any String :  tutorial gateway

 Please Enter the Character that you want to Replace :  t

 Please Enter the New Character :  M

 The Final String after Replacing First occurrence of 't' with 'M' = Mutorial gateway

程序：替换字符串中字符的第一次出现 示例 3

此程序替换第一个字符出现与第一个示例相同。但这次，我们使用了函数概念来分离逻辑。

/* C Program to Replace First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>

void Replace_FirstOccurrence(char *str, char ch, char Newch);
 
int main()
{
  	char str[100], ch, Newch;
  	int i = 0;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Replace :  ");
  	scanf("%c", &ch);
  	
  	getchar();
  	
  	printf("\n Please Enter the New Character :  ");
  	scanf("%c", &Newch);
  	
  	Replace_FirstOccurrence(str, ch, Newch);
  	
  	printf("\n The Final String after Replacing First occurrence of '%c' with '%c' = %s ", ch, Newch, str);
	
  	return 0;
}

void Replace_FirstOccurrence(char *str, char ch, char Newch)
{
	int i;

	for(i = 0; str[i] != '\0'; i++)
	{
		if(str[i] == ch)
		{
			str[i] = Newch;
  			break;
		}  
	}
}

 Please Enter any String :  learn c programming

 Please Enter the Character that you want to Replace :  e

 Please Enter the New Character :  @

 The Final String after Replacing First occurrence of 'e' with '@' = l@arn c programming