How can I fix the given compiler errors
Question
I am fairly new to the C language and I can't figure out how to fix these compiler errors that you can find at the end of the question. At the first error it says that it expects a int * but has given the type int ** What's the difference between these two? Would be great if you could explain in detail
#include <stdio.h>
#include <limits.h>
// Array format [DD,MM,YYYY]
int date[3];
int secondDate[3];
int correctFormat = 0;
// Constant texts
const char DAY_TEXT[] = "Enter the day of the first date: ";
const char MONTH_TEXT[] = "Enter the month of the first date: ";
const char YEAR_TEXT[] = "Enter the year of the first date: ";
const char DAY_ERROR[] = "Please enter the day in correct format DD";
const char MONTH_ERROR[] = "Please enter the month in correct format MM";
const char YEAR_ERROR[] = "Please enter year in correct format YYYY";
// ANSI color codes
#define RED "\x1b[31m"
#define GREEN "\x1b[32m"
#define RESET "\033[0m"
int checkDigits(int i)
{
/*
Fastest way to check number of digits in given integer
*/
if (i < 0)
i = (i == INT_MIN) ? INT_MAX : -i;
if (i < 10)
return 1;
if (i < 100)
return 2;
if (i < 1000)
return 3;
if (i < 10000)
return 4;
if (i < 100000)
return 5;
if (i < 1000000)
return 6;
if (i < 10000000)
return 7;
if (i < 100000000)
return 8;
if (i < 1000000000)
return 9;
}
void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
{
while (correctFormat == 0)
{
printf("%s", text);
scanf("%d", &dateVal);
if (checkDigits(dateVal) == 4)
{
correctFormat = 1;
}
else
{
printf(RED " %s \n" RESET, errorText);
}
}
correctFormat = 0;
}
int main()
{
dateInput(2, date[0], DAY_TEXT, DAY_ERROR);
dateInput(2, date[1], MONTH_TEXT, MONTH_ERROR);
dateInput(4, date[2], YEAR_TEXT, YEAR_ERROR);
dateInput(2, secondDate[0], DAY_TEXT, DAY_ERROR);
dateInput(2, secondDate[1], MONTH_TEXT, MONTH_ERROR);
dateInput(4, secondDate[2], YEAR_TEXT, YEAR_ERROR);
// Checking if the second date's year is less than the first one
if (secondDate[2] < date[2])
{
printf(GREEN "Second date is earlier than the first %d \n", checkDigits(secondDate[2]));
}
else if (secondDate[2] > date[2])
{
printf(RED "Second date is not earlier than the first \n");
}
// Checking if the second date's month is less than the first one
else if (secondDate[1] < date[1])
{
printf(GREEN "Second date is earlier than the first \n");
}
else if (secondDate[1] > date[1])
{
printf(RED "Second date is not earlier than the first \n");
}
// If months are equal then check the day
else if (secondDate[1] == date[1])
{
if (secondDate[0] < date[0])
{
printf(GREEN "Second date is earlier than the first \n");
}
else if (secondDate[0] == date[0])
{
printf(RED "The dates are basically the same \n ");
}
}
return 0;
}
task2cp.c: In function ‘dateInput’:
task2cp.c:58:17: warning: format ‘%d’ expects argument of type ‘int *’, but argument 2 has type ‘int **’ [-Wformat=]
58 | scanf("%d", &dateVal);
| ~^ ~~~~~~~~
| | |
| | int **
| int *
task2cp.c:59:25: warning: passing argument 1 of ‘checkDigits’ makes integer from pointer without a cast [-Wint-conversion]
59 | if (checkDigits(dateVal) == 4)
| ^~~~~~~
| |
| int *
task2cp.c:25:21: note: expected ‘int’ but argument is of type ‘int *’
25 | int checkDigits(int i)
| ~~~~^
task2cp.c: In function ‘main’:
task2cp.c:73:22: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
73 | dateInput(2, date[0], DAY_TEXT, DAY_ERROR);
| ~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:73:27: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
73 | dateInput(2, date[0], DAY_TEXT, DAY_ERROR);
| ^~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:73:37: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
73 | dateInput(2, date[0], DAY_TEXT, DAY_ERROR);
| ^~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
task2cp.c:75:22: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
75 | dateInput(2, date[1], MONTH_TEXT, MONTH_ERROR);
| ~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:75:27: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
75 | dateInput(2, date[1], MONTH_TEXT, MONTH_ERROR);
| ^~~~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:75:39: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
75 | dateInput(2, date[1], MONTH_TEXT, MONTH_ERROR);
| ^~~~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
task2cp.c:77:22: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
77 | dateInput(4, date[2], YEAR_TEXT, YEAR_ERROR);
| ~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:77:27: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
77 | dateInput(4, date[2], YEAR_TEXT, YEAR_ERROR);
| ^~~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:77:38: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
77 | dateInput(4, date[2], YEAR_TEXT, YEAR_ERROR);
| ^~~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
task2cp.c:79:28: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
79 | dateInput(2, secondDate[0], DAY_TEXT, DAY_ERROR);
| ~~~~~~~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:79:33: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
79 | dateInput(2, secondDate[0], DAY_TEXT, DAY_ERROR);
| ^~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:79:43: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
79 | dateInput(2, secondDate[0], DAY_TEXT, DAY_ERROR);
| ^~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
task2cp.c:81:28: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
81 | dateInput(2, secondDate[1], MONTH_TEXT, MONTH_ERROR);
| ~~~~~~~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:81:33: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
81 | dateInput(2, secondDate[1], MONTH_TEXT, MONTH_ERROR);
| ^~~~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:81:45: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
81 | dateInput(2, secondDate[1], MONTH_TEXT, MONTH_ERROR);
| ^~~~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
task2cp.c:83:28: warning: passing argument 2 of ‘dateInput’ makes pointer from integer without a cast [-Wint-conversion]
83 | dateInput(4, secondDate[2], YEAR_TEXT, YEAR_ERROR);
| ~~~~~~~~~~^~~
| |
| int
task2cp.c:53:39: note: expected ‘int *’ but argument is of type ‘int’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~^~~~~~~~~
task2cp.c:83:33: warning: passing argument 3 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
83 | dateInput(4, secondDate[2], YEAR_TEXT, YEAR_ERROR);
| ^~~~~~~~~
task2cp.c:53:55: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~
task2cp.c:83:44: warning: passing argument 4 of ‘dateInput’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
83 | dateInput(4, secondDate[2], YEAR_TEXT, YEAR_ERROR);
| ^~~~~~~~~~
task2cp.c:53:68: note: expected ‘char *’ but argument is of type ‘const char *’
53 | void dateInput(int correctDigits, int dateVal[], char text[], char errorText[])
| ~~~~~^~~~~~~~~~~
2 answers
solution1
0 2021-10-25 17:09:05
The int * type is a Pointer to an Integer. The int ** type is a Pointer to a Pointer to an Integer.
Basically Imagine that when you create a Variable in your memory, you'll give it a Name that will be the way you refer to that. If you want, you can get the Pointer to the Variable, a Pointer to a Variable will memorize the index of your variable in memory (like 0xf325... and similar). That means you can pass the Pointer to any function/part of program, and you will always work in this part of the memory where your variable is stored in!
It's more likely you have to watch a guide that explains variables passed by Value and by Reference.
For example in the first Warning it says you are passing a int** insthead of int*. As you can see in your code as Argument you passed &dateVal , but dateVal is probably of type int* and passing in the Pointer of a int* will return as a pointer of a int**. A possible fix will be to pass in dateVal without the "&" before it, so you will pass a int* as requested. I don't know if it will do what you expect to, but that's why you have the Error!
solution2
0 2021-10-25 17:09:16
int dateVal[] as a parameter is just another way of writing int *dateVal . Since dateVal is already a pointer to where you want to write, you want scanf("%d", dateVal)
Except you don't pass a pointer for dateVal . dateInput(2, date[0], ...) should be dateInput(2, &date[0], ...) or dateInput(2, date+0, ...) .
Finally, char text[] and char errorText[] should have const added since you don't modify the pointed values, and to permit the function to accept constant values.
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