Caesar Cipher Algorith Shifting C [closed] - c

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So I was writing a C program to make use of caesar algorithm using a custom table, where I will give the table and shifting will be done using that table e.g the text "abc" according to table "abc" with key=1 should be ciphered as bca, however i am having difficulty on the last characters if key+index of letter is higher than the length of the table stored here is my code
void encrypt (char table[],char entext[],char text[],int key)
{
int i,j;
int k = strlen(table);
//int result = (key + k);
for (i=0;i<strlen(table);++i)
{
j = 0;
if (text[i]!='\0')
{
while (text[i]!=table[j])
{
j++;
}
if ((j+key)>k)
{
j=(j+key)%k;
//j = (result - j);
}
else
j = j + key;
entext[i] = table[j];
}
}
entext[i+1] = '\0';
puts(entext);
}
int main()
{
char table[100] , text[100] , entext[100] , c;
int i , j , key;
printf("Enter the text : ");
gets(text);
printf("Enter the table : ");
gets(table);
printf("Enter the key : ");
scanf("%d",&key);
encrypt(table,entext,text,key);
system("pause");
return 0;
}

Answer 1

if ((j+key)>k)
should be
if ((j+key)>=k)
Besides, this check is completely unnecessary because of how mod works. I will take the liberty to rewrite your code so it looks nicer:
void encrypt (char table[],char entext[],char text[],int key)
{
int i,j;
int k = strlen(table);
//int result = (key + k);
for (i=0;i<strlen(table);++i)
{
if (text[i]!='\0')
{
for(j=0; text[i] != table[j] ;j++);
entext[i] = table[(j+key)%k];
}
}
entext[i+1] = '\0';
puts(entext);
}
I believe you could make this "table" lookup more efficient by indexing the value of the char itself, but unless you are dealing with pretty big input, this won't really make a difference.

Answer 2

void encrypt (char table[], char entext[], char text[], int key) {
int i,j;
int k = strlen(table);
for (i=0;text[i];++i){
for(j=0;table[j] && text[i]!=table[j];++j)
;
if(table[j]=='\0')//character not find at table
entext[i] = text[i];//Not slide. // or Error?
else {
j += key;
if(j>=k)
j -= k;//j = j % k
entext[i] = table[j];
}
}
entext[i] = '\0';
puts(entext);
}