c++ - 如何在c中查找同一字符串中该字符的第一次重复出现

Question

如何让重复字符第一次出现时仅打印该字符。区分大小写或不区分大小写无关紧要。例如对于输入=“opuott”答案=o/O 输入=“kuttu”答案=t/T

#include<stdio.h>
#include<string.h>
int main(){
        int i,j,diff=0,min=0;
        char arr[100],var;
        printf("Enter the string to check for: ");
        scanf("%s",&arr);
        for(i=0;i<strlen(arr);i++){
                arr[i]=toupper(arr[i]);
                printf("%c ",arr[i]);
        }
        printf("\n");
        for(i=0;i<strlen(arr);i++){
                for(j=i+1;j<strlen(arr);j++){
                        if(arr[i]==arr[j]){
                                diff=j-i;
                                //THIS IF BLOCK IS USED FOR FIRST CONDITION FAILURE OF MIN AND DIFFERENCE       
                                if(diff > min){
                                        min=diff;
                                        var=arr[i];
                                }
                                //THIS ELSE BLOCK IS USED FOR REGULAR CHECK FOR THE MIN AND DIFF AND ADJUST MIN TO DIFF ACCORDINGLY
                                else if(diff < min){
                                        min=diff;
                                        var=arr[i];
                                }
                        }
                }
        }
        printf("Final Answer : %c\n",var);
        return 0;
}

Answer 1

在 C 中，区分大小写的解决方案可以是这样的:

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

    int repeated_char(char arr[],bool char_arr[],size_t len){
       int i;
       for(i=0;i<len;i++){
             if (char_arr[arr[i]] == true)
                 return arr[i];
             else
                 char_arr[arr[i]] = true;
        }
       return -1;
    }

    int main(){

       char arr[100];
       bool char_arr [256];

       printf("Enter the string to check for: ");
      scanf("%100s",&arr);
      size_t arr_len = strlen(arr);
      memset(char_arr,false,sizeof(char_arr));
      char ans = repeated_char(arr,char_arr,arr_len);
      if (ans == -1)
          printf("No repeated chars were found");
      else
          printf("%c",ans);
    }

输入:“nabc-=1nabc”

输出:n