Simple Menu Program in C 2

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char ch[200];

void print() {
    printf("\nEnter the message: ");
    gets(ch);
}

void ntime() {
    int n, i;
    n = strlen(ch);
    printf("The above message is printed %d times below:", n);
    for (i = 0; i < n; i++)
        printf("\n%s", ch);
    printf("\n");
}

void revo() {
    printf("The message in reverse order is: ");
    printf("%s\n", strrev(ch));
}

void change() {
    int i, j;
    i = strlen(ch);
    for (j = 0; j < i; j++) {
        if (ch[j] >= 'a' && ch[j] <= 'z')
            ch[j] -= 32;
        else if (ch[j] >= 'A' && ch[j] <= 'Z')
            ch[j] += 32;
        else
            continue;
    }
    puts(ch);
}

void block() {
    int i, j, n;
    n = strlen(ch);
    printf("The given message in block staircase pattern is: \n");
    for (i = 0; i < n; i++) {
        for (j = 0; j <= i; j++)
            printf("%c", ch[j]);
        printf("\n");
    }
    printf("\n");
}

void main() {
    int a;
    while (1) {
        printf("\nMENU");
        printf("\n1.Print message no. of time as per its length");
        printf("\n2.Print the message in reverse order");
        printf("\n3.Print the message in block staircase pattern");
        printf("n4.Print the message in capital letters and vice versa");
        printf("\n5.Exit from program");
        printf("\n\nEnter your choice: ");
        scanf("%d", &a);
        switch (a) {
        case 1:
            ntime();
            break;
        case 2:
            revo();
            break;
        case 3:
            block();
            break;
        case 4:
            change();
            break;
        case 5:
            exit(1);
        default:
            printf("Invalid choice\n");
        }
    }
}