is working alright but it doen't print the first characters. And you plse check them for me again


/*header file*/
#include <stdio.h>
#include <ctype.h>
#define MAX 1000
#define LEN 1000

/*global declaration*/
void show_menu();
void do_menu_choice(char ch);
char get_choice();
void convert(char str[]);
void rev(char string[50]);
int done;
char c[] = " ";

/*function main*/
int main(int argc, char **argv)
{

done = 0;


show_menu();
do_menu_choice(get_choice());




return 0;
}

void show_menu() {

/*menu print outs from A to F*/
printf(" \n");
printf("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$\n");
printf("$ Choose A Menu A--F $\n");
printf("$ ..................... $\n");
printf("$ A Invert Character case of a line text $\n");
printf("$ B Reverse Words $\n");
printf("$ C Squeeze Spaces $\n");
printf("$ D Most frequently occuring letter pair $\n");
printf("$ E Trace of this program $\n");
printf("$ F Exit $\n");
printf("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$\n");
printf(" \n");

}

char get_choice()
{
char ch;

while(ch != 1) {

printf("Enter choice:\n");
ch = getchar();

if(ch >= 'A' && ch <= 'F')
return ch;
}
printf("Invalid choice\n");

}


void do_menu_choice(char ch)
{


switch(ch) {

case 'A':
printf("Enter a string\n\n");
scanf("%s\n", c);
convert(c);
break;
case 'B':
printf("Enter a string\n\n");
scanf("%s\n", c);
rev(c);
break;
case 'C':
printf("Hello\n");
break;
case 'D':
printf("Hoooo\n");
break;
case 'E':
printf("Tahhhaaa\n");
break;
case 'F':
printf("Bye \n");
done = 1;
break;
default:
printf("Funny when using windows\n");

}
}


/*function to convert character of text*/
void convert(char str[])
{


char ch[MAX];
int i;
scanf("%c",ch);

if (fgets(ch, MAX, stdin) !='\0')
{
for(i=0; ch[i]; ++i)
{
if(isupper( (int)ch[i]) )
{
ch[i] = tolower(ch[i]);
}

else
{
ch[i] = toupper(ch[i]);
}
}
printf("\nThe Converted text: %s \n",ch);
}
else
{
printf("\nNo input fetched!\n");
}


}


/*function to reverse character of text*/
void rev(char string[1000])
{
int i,j;
char text[LEN];
char r_text[LEN];
fgets(text, LEN, stdin);
i = strlen(text) - 1; // -1 removes \n
j = 0;

while(i--)
r_text[j++] = text[i];
r_text[j]='\0';

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

scanf only gets one char. Use fgets.

in rev function:
1 you don't need variable text if you passed value to funtion in string[1000]. Use the local variable that you passed to the function.
2 you don't need this line if you've already gotten the input from user and passed to function: fgets(text, LEN, stdin); Put this line in place of scanf above and change rev(c) to rev(text);

I didn't review all of your code, but I'm not sure you'll need scanf anywhere. If you're getting stings, use fgets.
Get rid of #define LEN 1000 because you've already defined MAX as 1000. Replace LEN with MAX in your code.

Thats just a few of the problems