Hi CS50 gang!

I'm really enjoying the course, but my brain hurts already at week 2. I've noticed an error when compiling a programme in C when I try to declare a variable inside a FOR loop in C (example below).

I just move my variable declaration to above the FOR loop, but I have two questions about this:

1. Why does this happen? Is it because the loop tries to declare the variable each time it iterates?

2. Does it cause problems to declare the variable (int letter_count) above the loop, like I have done in the example below? Or is there a better convention for declaring variables?

 int letter_count = 0;
    //loop to break text string into chars
    for (int i = 0, n = strlen(text); i < n; i++)
    {
        //check if char i is lower or upper and increment letter-count by 1 if true
        if (isupper(text[i]) || islower(text[i]))
        {
            letter_count++;
        }
        
        printf("%c", text[i]);
    }

Thank you!

Hello, I'm new to programming and while coding my example program I ran into an issue that I've been trying to figure out how to resolve. When print_Menu_Info(); executes and it tries to execute print_Customer_Table(&c); I encounter the error in the title.

sales.c:101:24: error: use of undeclared identifier 'c'

Even though the line is being declared in line 12.

struct customer c = empty_customer;

#include <stdio.h>
#include <stdlib.h>
#include "sales.h"

int main(void)
{
    menu_update();
    return 0;
}

void menu_update(void){
    struct customer c = empty_customer;
	float f = 0.00;
	int i = 0;
	while (1) {
	    cls();
	    print_Menu_Info();
	    switch(get_User_Input()){
	        case 1:
				printf("Customer First Name: ");
				scanf("%s",c.first_Name);
	            break;
	        case 2:
				printf("Customer Last Name: ");
				scanf("%s",c.last_Name);
	            break;
	        case 3:
				printf("Customer Amount: ");
				scanf("%f",&f);
				c.amount = f;
	            break;
	        case 4:
				printf("Customer Card Number: ");
				scanf("%s",c.card_Number);
	            break;        
	        case 5:
				printf("Customer Card Expiration Month: ");
				scanf("%i",&i);
				c.card_Expiration_Month = i;
	            break;
	        case 6:
				printf("Customer Card Expiration Year: ");
				scanf("%i",&i);
				c.card_Expiration_Year = i;
	            break;
	        case 7:
				printf("Sales Person: ");
				scanf("%s",c.sales_Person);
	            break;
            case 8:
                print_Customer_Table(&c);
                break;
            case 9:
                c = empty_customer;
                break;
	        case 10:
	            exit(0);
	        default:
	            printf("Incorrect action ID!\n");
	            break;
	    }    
	}
}

void cls(void){
    printf("\033c");
}

int get_User_Input(){
	int a = 0;
    char line[32];
    printf("Please input an action ID: ");
	if (fgets(line, sizeof(line), stdin) != NULL) {
    	sscanf(line, "%i", &a);
    	cls();
    }
	return a;
}


void print_Customer_Table(struct customer *cp){
    printf(
    "1. Customer First Name: %s\n"
    "2. Customer Last Name: %s\n"
    "3. Customer Amount: $%.2f\n"
    "4. Customer Card Number: %s\n"
    "5. Customer Card Expiration Month: %i\n"
    "6. Customer Card Expiration Year: %i\n"
    "7. Sales Person: %s\n",
    cp->first_Name,
    cp->last_Name,
    cp->amount,
    cp->card_Number,
    cp->card_Expiration_Month,
    cp->card_Expiration_Year,
    cp->sales_Person);
}

void print_Menu_Info(void){
	print_Customer_Table(&c);
	printf(
	"If you would like to update a value type the value you would like to update(1-7)\n"
    "If you would like to send this as a email type 8\n"
    "If you would like to clear all customer data type 9\n"
    "If you would like to exit this program type 10\n");
}                

and sales.h

#define NAME_LEN_MAX 128
#define CARD_NUM_LEN_MAX 16
struct customer {
    char first_Name[NAME_LEN_MAX + 1];
    char last_Name[NAME_LEN_MAX + 1];
    float amount;
    char card_Number[CARD_NUM_LEN_MAX + 1];
    int card_Expiration_Month;
    int card_Expiration_Year;
    char sales_Person[NAME_LEN_MAX + 1];
};
const static struct customer empty_customer = {{""},{""},0.00,{""},0,0,{""}};
void print_Customer_Table(struct customer *cp);
void print_Menu_Info(void);
void cls(void);
int get_User_Input();
void menu_update(void);

I'm having difficulty figuring out why it won't recognize this function passing parameters, in the int main function. I'm trying to pass the computeoffSet function, and it doesn't like the parameters passed within it. Calls them an undeclared identifier, and I believe I have them declared above. I would appreciate some advice on the problem, for which I'd be grateful.

#include <iostream>
#include <iomanip>
using namespace std;

int getMonth()
{
int usermonth;
cout << "Enter a month number: ";
cin >> usermonth;
return usermonth;
}
int getYear()
{
int useryears;
cout << "Enter year: ";
cin >> useryears;
return useryears;
}

int leapCheck(int month, int years)
{
if(month == 2)
{
if((years % 400 == 0) || (years % 4== 0 && years % 100 != 0))
return 29;
else
return 28;
}
}
int calcDays(int month, int years)
{
int userday = 0;
{
if(month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
return userday + 31;
else
return userday + 30;
}
return userday;
}

int computeoffSet(int month, int years)
{
int offset = 0;
for(int y = 0; y < 1753; y++)
offset = (offset + 365 + calcDays(month, years)) % 7;
for (int m = 1; m < month; m++)
offset = (offset + calcDays(month, years)) % 7;
return offset;
}
void display(int month, int years, int offset)
{
int numDays = calcDays(month, years);
cout << " Su Mo Tu We Th Fr Sa";
int position = 6;
while(position != offset)
{
cout << " ";
position += 1;
if(position > 6)
position = position - 7;
}
for(int count = 1; count <= numDays; count++)
{
cout << setw(4) << count;
position += 1;

if(position == 7)
position = position - 7;
if(position == 6)
cout << endl;
}
if(position < 6)
cout << endl;
}

int main()
{
int userMonth = getMonth();
int offset = computeoffSet(usermonth, useryears);
int userYears = getYear();
display(userMonth, offset, userYears);
return 0;
}

int total = 0;   
    for (int i= 0; word[i] != '\0'; i++)
    ;
    {
       char c = word[i];     
       if (isalpha(c))
           total += POINTS[get_index(c)];
    }    
    return total;
        
}

int get_index(char c)
{
    return tolower(c) - 'a';

When I compile the code I get undeclared identifier 'i'. But when declare it I get declaration shadows a variable in the global scope [-Werror,-Wshadow]. Please help

Ive done some research and everyone that seemed to have this problem already didn't declare the variable outside of the loops or if statements that they were used it. I made sure to do it before and I cant seem to get this darn thing working.

Its mostly practice so if anyone can tell me why Id appreciate it!

I get the error Errors

error C2143: syntax error : missing ';' before 'type' Line 0

and

error C2065: 'CountTotal' : undeclared identifier (This one comes up 4 times) Line 10

Now this is driving me crazy. It doesn't work in my compiler, but it works on the website compiler. Ive been trying to fix this for two days. Any ideas? I'm using Microsoft visual express c++ 2011

http://ideone.com/5ifRPT

Hi,

So I'm very new to programming and am currently undertaking the Harvard CS50 course. Attempting lab 2, I have come across the following error:

scrabble.c:17:34: error: use of undeclared identifier 'word'

for (int i = 0, len = strlen(word); i < len; i++)

This error is confusing the heck out of me, as there are lines of code beneath this one that are unaffected.

The top of my code (prior to line 17) introduces the identifier as int compute_score(string word);. But for some reason, the "word" on line 17 is unaffected by the declaration, while lines of code beneath it that also include "word" are colored orange correspondingly. The "word" on line 17 is for some reason, uncolored.

Sorry if this makes little sense, half asleep trying to do this and am beating myself up a bit.

Thanks.