即使使用命令 if(*str == 'stop') 并输入 stop，'While' 循环也不会停止

Question

I want to write a function that replaces all occurrences of a character c with a character e. The functions seems to be working. However in the main, I want to be able to repeatedly enter a string, scan the character to be replaced, scan the character that will replace, and print the before and after, UNTIL the entered string is 'stop'. How do i do this? I have tried defining 'stop' as a constant character string but that did not work. This is what my code looks like:

#include <stdio.h>
#include <string.h>

void replaceAll(char *str, char c, char e){
     for(int i = 0; str[i] != '\n'; i++){
        if(str[i] == c){
        str[i] = e;
        }
     }
     return; 
}

int main(){
    char str[80], c, e;
    //repeatedly enter string;
    while(*str != '\n'){
        fgets(str, sizeof(str), stdin);
        //jump out of loop
        if(*str == 'stop')
        getchar();
        scanf("%c", &c);
        getchar();
        scanf("%c", &e); 

        printf("replace all occurances of %c with %c in\n", c, e);
        printf("%s", str);
        //calls function
        replaceAll(str, c, e);
        printf("%s", str);
    }
    return 0; 
}

Any help is very much appreciated:)

Answer 1

I assume you want the user to define c and e once before the loop starts. Then move the following code to anywhere before the while loop starts. Best if you inform the user what to enter and not just use scanf() .

    printf(“please enter the char to find\n”);
    getchar();
    scanf("%c", &c);
    printf(“please enter the char to replace\n”);
    getchar();

    scanf("%c", &e); 

The main problem is with the following line:

// jump out of loop
if(*str == 'stop')

First, a single bracket is used for single characters and not for strings, where you should use brackets (“).

Second, use strcmp ().

Third, to jump out of the loop, use break; .

// jump out of loop
if(strcmp (&str[0], “stop\n”) == 0)
{
      break;
}