在 C 中使用自定义字母解码字符数组

Question

#include<stdio.h>

int main(){

    int i,j;
    char kulcs[27]="DKVQFIBJWPESCXHTMYAUOLRGZN",kod='D',szoveg[256]="fndcdahqweehufsfnhtyhbydchcdcwEHQHSfaQFEHQHS";

    if(kod=='D'){
        for(i=0;kulcs[i]!='\0';i++){
            for(j=0;szoveg[j]!='\0';j++){
                if(kulcs[i]==szoveg[j]){
                        szoveg[j]=i+65;
               }else if(kulcs[i]==szoveg[j]-32){
                        szoveg[j]=i+97;
                }
            }   
        }   
        printf("%s\n",szoveg);
    }

    return 0;
}

kulcs stores the alphabet, szoveg is the word I want to decode, while keeping upper and lower case letters intact.

expected result:

ezamasodikkotelezoprogramomamiKODOLesDEKODOL

what the code does is:

kzsqssudikkutkvkzupwuxwsquqsqiKUDUVksDKKUDUV

What did I do wrong?

Answer 1

Your loops are in the wrong order. You loop through the alphabet and inside that loop you loop through the word. Think what happens.

An example:

Let's say the transformations are

A->B
B->C

You input word ABC

Your code starts looping through the transformations. First it checks all A's and changes them to B's, so you get BBC. Then it checks all B's and transforms them to C's, so you get CCC.

What you should do is loop through the input and check which transform fits. In this example you first get A, check that there's a transform A->B, so this becomes B. Your output is just B. Then there's a B, which must be transformed into C, so you have now BC. Then is C, no transform, so it's BCC.

So change the j and i loops around and see what happens.

for(j=0;szoveg[j]!='\0';j++){
    for(i=0;kulcs[i]!='\0';i++){

Also you can break the loop if either of the conditions fits, since there won't be another suitable condition after that.