string manipulation

#include <stdio.h>

int main(void) {
    int ch = 1;
    while (ch != 5) {
        printf("MENU OPTIONS:\n1. String concatenation\n2. String comparison\n3. String length\n4. String copy\n5. Exit\n");
        printf("Enter choice: ");
        scanf("%d", &ch);

        // Initializing strings
        char str1[100];
        char str2[100];

        if (ch == 1) {
            char str[100];
            printf("Enter first string: ");
            scanf("%s", str1);
            printf("Enter second string: ");
            scanf("%s", str2);

            // Printing original strings
            printf("Original strings: %s, %s\n", str1, str2);

            // Performing operation
            int i;
            for (i = 0; str1[i] != '\0'; i++) {
                str[i] = str1[i];
            }
            int index = i;
            for (i = 0; str2[i] != '\0'; i++) {
                str[index+i] = str2[i];
            }

            printf("Concatenated string: %s\n", str);
        }
        else if (ch == 2) {
            printf("Enter first string: ");
            scanf("%s", str1);
            printf("Enter second string: ");
            scanf("%s", str2);  

            int flag = 0;

            for (int i = 0; str1[i] != '\0'; i++) {
                if (str1[i] != str2[i]) {
                    flag = 1;
                    break;
                }
            }

            if (flag) {
                printf("Strings are not equal\n");
            }
            else {
                printf("Strings are equal\n");
            }
        }
        else if (ch == 3) {
            printf("Enter string: ");
            scanf("%s", str1);

            int count = 0;
            for (int i = 0; str1[i] != '\0'; i++) {
                count++;
            }

            printf("Length of string: %d\n", count);
        }
        else if (ch == 4) {
            printf("Enter string: ");
            scanf("%s", str1);

            printf("Original string: %s(%p)\n", str1, &str1);

            for (int i = 0; str1[i] != '\0'; i++) {
                str2[i] = str1[i];
            }

            printf("Copied string: %s(%p)\n", str2, &str2);
        }
        else if (ch != 5) {
            printf("\nInvalid option\n\n");
        }
    }

    printf("Exit..\n");
    return 0;
}