main.c

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

#define OK       0
#define NO_INPUT 1
#define TOO_LONG 2

static int getLine (char *prmpt, char *buff, size_t sz) {
    int ch, extra;

    // Get line with buffer overrun protection.
    if (prmpt != NULL) {
        printf ("%s", prmpt);
        fflush (stdout);
    }
    if (fgets (buff, sz, stdin) == NULL)
        return NO_INPUT;

    // If it was too long, there'll be no newline. In that case, we flush
    // to end of line so that excess doesn't affect the next call.
    if (buff[strlen(buff)-1] != '\n') {
        extra = 0;
        while (((ch = getchar()) != '\n') && (ch != EOF))
            extra = 1;
        return (extra == 1) ? TOO_LONG : OK;
    }

    // Otherwise remove newline and give string back to caller.
    buff[strlen(buff)-1] = '\0';
    return OK;
}

int main() {
    int t,i,j;
    int caps=0;

    int rc;
    char buff[10005];

    scanf("%d\n", &t);
    for(i=0;i<t;i++)
    {
        rc = getLine ("", buff, sizeof(buff));
        if (rc == NO_INPUT) {
            // Extra NL since my system doesn't output that on EOF.
            printf ("\n");
            return 1;
        }

        if (rc == TOO_LONG) {
            printf ("\n");
            return 1;
        }

        if(isupper(buff[0])) {
            // CAPS all
            caps = 1;
        } else
            caps = 0;

        for(j=0; j < strlen(buff); j++)
        {
            if(caps == 1) {
                buff[j] = toupper(buff[j]);
            }else {
                buff[j] = tolower(buff[j]);
            }
        }

        printf ("%s\n", buff);
    }

	return 0;
}