Thread: Code review needed

Hello there. This is a small program that reads a line from the screen, takes the ASCII values from the entered text, and edits it. Next, the ASCII values are reintepreted(am i misspelling?) as text, and displayed. However, my final output has (allways?) at least 7 characters, even if you enter only one. I'm allso trying to accomplish, that the part of the string which isn't filled, will be printed empty. In spaces.

compiled with -std=c99.

Code:

#include <stdio.h>

int main(){
    int maxsize;
    printf("How long is your message?\n");
    scanf("%d",&maxsize);
    int iinput[maxsize], ioutput[maxsize], key, c;
    char cinput[maxsize], coutput[maxsize];
    
    printf("What is the message you want to (de)code?\n");
    scanf("%s",cinput);
    for(int i=0;i<maxsize;i++){
        iinput[i]=(int)cinput[i];
    }
    printf("Thank you. ");
    printf("What is your key?\n");
    scanf("%d",&key);
    lchoice:
    printf("1 for coding, 2 for decoding.\n");
    scanf("%d",&c);
    switch (c)
    {
        case 1:
            for(int j=0;j<maxsize;j++){
                ioutput[j]=iinput[j]+key;
            }
            for(int k=0;k<maxsize;k++){
                coutput[k]=(char)ioutput[k];
            }
            break;
        case 2:
            for(int j=0;j<maxsize;j++){
                ioutput[j]=iinput[j]-key;
            }
            for(int k=0;k<maxsize;k++){
                coutput[k]=(char)ioutput[k];
            }
            break;
        default:
            printf("You did not enter 1 or 2.\n");
            goto lchoice;
    }
    printf("This is the coded message:\n");
    printf("%s\n",coutput);
    system("pause");
    return(0);
}

I would really appreciate some help. Thanks in advance.