pvjc24/du1/program.c

#include <stdio.h>
#include <ctype.h>

int main() {
    int c;
    char output;
    int count_line = 0;

    while ((c = getchar()) != EOF) {
        if (islower(c)) {
            output = toupper(c);
        }
        else if (isupper(c)) {
            output = tolower(c);
        } 
        else if (isgraph(c) || c == ' ') {
            output = c;
        }
        else {
            output = c; 
        }
        putchar(output);
        if (c == '\n') { 
            count_line++;
        }
    }
   // printf("Number of lines: %d\n", count_line); 
    return 0;
}