Using C language, alter the program such that only the correct output is sent to the standard output stream (stdout), while error and help messages are sent to the standard error stream (stderr).

(Hint:use fprintf.)

See the expected output listed in the comment at the top of main. c for an example of what should go to stdout.

#include
#include
#include
#include "smp0_tests. h"

#define LENGTH(s) (sizeof(s) / sizeof(*s))

/* Structures */
typedef struct {
char *word;
int counter;
} WordCountEntry;

int process_stream(WordCountEntry entries[], int entry_count)
{
short line_count = 0;
char buffer[30];

while (gets(buffer)) {
if (*buffer == '.')
break;
/* Compare against each entry */
int i = 0;
while (i < entry_count) {
if (!strcmp(entries[i].word, buffer))
entries[i].counter++;
i++;
}
line_count++;
}
return line_count;
}

void print_result(WordCountEntry entries[], int entry_count)
{
printf("Result:\n");
while (entry_count-- > 0) {
printf("%s:%d\n", entries->word, entries->counter);
}
}

void printHelp(const char *name)
{
printf("usage: %s [-h] ... \n", name);
}

int main(int argc, char **argv)
{
const char *prog_name = *argv;

WordCountEntry entries[5];
int entryCount = 0;

/* Entry point for the testrunner program */
if (argc > 1 && !strcmp(argv[1], "-test")) {
run_smp0_tests(argc - 1, argv + 1);
return EXIT_SUCCESS;
}

while (*argv != NULL) {
if (**argv == '-') {

switch ((*argv)[1]) {
case 'h':
printHelp(prog_name);
default:
printf("%s: Invalid option %s. Use -h for help.\n",
prog_name, *argv);
}
} else {
if (entryCount < LENGTH(entries)) {
entries[entryCount].word = *argv;
entries[entryCount++].counter = 0;
}
}
argv++;
}
if (entryCount == 0) {
printf("%s: Please supply at least one word. Use -h for help.\n",
prog_name);
return EXIT_FAILURE;
}
if (entryCount == 1) {
printf("Looking for a single word\n");
} else {
printf("Looking for %d words\n", entryCount);
}

process_stream(entries, entryCount);
print_result(entries, entryCount);

return EXIT_SUCCESS;
}