Unexpected Run Error, please help.

[digitaldan]

Hello All,

I've spent a ton of time on this code and am all of a sudden having a strange occurrence. While executing the case1 in my switch, it blasts through without accepting the user keyboard input and just runs the whole code. I put this section of code (the case 1) in it's own separate *.c file and it executed perfectly. Any help is greatly appreciated!

Thanks,

Dan

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <math.h>
long int factorial(int n_end);
void clear_message(char* input);
int main()
{
        int menu, i, j, n, n_end;
        double y, x, exp, sum, sum_2;
        char message[111]={'\0'};
        printf("\nHomework 4:\n\n");
        printf("There are two parts: part 1 and part 2.\n");
        printf("Enter the part number to execute (1 or 2):");
        scanf("%d", &n);
        switch(n){
            case 1:
                printf("\nPart I:\n\n");
                printf("Enter your message:");
                fgets(message, 111, stdin);
                printf("\nYour message is: %s\n\n", message);
                clear_message(message);

                int length=strlen(message);
                char* reverse = (char*) malloc(length + 1);
                for(i=0,j=length-1;j>=0;--j,++i)
                {
                reverse[i] = message[j];
                }
                reverse[i] = '\0';
                printf("Reversed String is: %s\n\n", reverse);
                break;
            case 2:
                printf("\nPart II:\n\n");
                printf("Series evaluation: x^n/n! from n=0 to n=n_end.\n");
                printf("\n");
                printf("Enter x, a real number, and n_end, a large positive interger.\n");
                scanf("%g %d", &x, &n_end);
                printf("\nThe values entered are: x = %g and n_end = %4d.\n\n", x, n_end);
                for (n=0, sum=0.0;n<n_end;n++){
                sum = sum + (pow(x,n)/(factorial(n)));
                }
                printf("The sum of %d terms of %g^%d/%d! is %g.\n", n_end, x, n_end,n_end, sum);
        exp = pow(2.718281828,x);
        printf("The true value for exp(%g) is %16.8e.\n", x, exp);
        break;
            default:
                printf("part %d does not exist.\n", menu);
}
        printf("\n");
        exit(0);// optional
}

long int factorial(int n_end)
 {
  if (n_end<=1)
        return(1);
  else
        n_end=n_end*factorial(n_end-1);
        return(n_end);
 }
void clear_message(char* input)
{
        char* k=0;
        if(k=strrchr(input, '\n'))
        *k='\0';
}

The instructions were to accept user inputted message, redisplay message then reverse letters and words. This is all done in C.

[gerard4143]

I really have to ask, what run time error is expected?

All kidding aside take a look at the line I added. This forum had a real good sticky on problems and remedies when dealing with input buffers...I would look it up..

A few notes on sytle

comments in standard C are /*something*/ not //something

The C language ignores whitespace so use programmers use this feature to layout their programs in a very logical readable/manner. Please consider this the next time you post....Whitespace can be good if used in a consistent and logical manner.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
long int factorial(int n_end);
void clear_message(char* input);
int main()
{
        int menu, i, j, n, n_end;
        double y, x, exp, sum, sum_2;
        char message[111]={'\0'};
        printf("\nHomework 4:\n\n");
        printf("There are two parts: part 1 and part 2.\n");
        printf("Enter the part number to execute (1 or 2):");
        scanf("%d", &n);
        switch(n){
            case 1:
                printf("\nPart I:\n\n");
                printf("Enter your message:");
		while (fgetc(stdin) != '\n') {}/*this line clears the input buffer*/
                fgets(message, 111, stdin);
                printf("\nYour message is: %s\n\n", message);
                clear_message(message);

                int length=strlen(message);
                char* reverse = (char*) malloc(length + 1);
                for(i=0,j=length-1;j>=0;--j,++i)
                {
                reverse[i] = message[j];
                }
                reverse[i] = '\0';
                printf("Reversed String is: %s\n\n", reverse);
                break;
            case 2:
                printf("\nPart II:\n\n");
                printf("Series evaluation: x^n/n! from n=0 to n=n_end.\n");
                printf("\n");
                printf("Enter x, a real number, and n_end, a large positive interger.\n");
                scanf("%lf %d", &x, &n_end);
                printf("\nThe values entered are: x = %g and n_end = %4d.\n\n", x, n_end);
                for (n=0, sum=0.0;n<n_end;n++){
                sum = sum + (pow(x,n)/(factorial(n)));
                }
                printf("The sum of %d terms of %g^%d/%d! is %g.\n", n_end, x, n_end,n_end, sum);
        exp = pow(2.718281828,x);
        printf("The true value for exp(%g) is %16.8e.\n", x, exp);
        break;
            default:
                printf("part %d does not exist.\n", menu);
}
        printf("\n");
        exit(0);
}

long int factorial(int n_end)
 {
  if (n_end<=1)
        return(1);
  else
        n_end=n_end*factorial(n_end-1);
        return(n_end);
 }
void clear_message(char* input)
{
        char* k = NULL;

        if((k = strrchr(input, '\n')) == NULL)
        	*k = '\0';
}

[digitaldan]

While I appreciate your help, I do not need a lecture on the organization of my code. A simple "You need to add a line to clear your input buffer" would have sufficed.

I am no programmer, nor do I ever plan on being one. This is just a basic C/C++ class required for my major to which the instructor continually points out to us that we will probably never use this again once we are done.

[gerard4143]

While I appreciate your help, I do not need a lecture on the organization of my code. A simple "You need to add a line to clear your input buffer" would have sufficed.

I am no programmer, nor do I ever plan on being one. This is just a basic C/C++ class required for my major to which the instructor continually points out to us that we will probably never use this again once we are done.

Well we 'the people of this forum' don't appreciate posters who can't even bother to present their code in a readable fashion and still expect prompt and free help...