8
votes
Accepted
What happens under the hood when performing a cast?
Lets say you have the following code:
short myShort = 23948;
byte myByte = (byte)myShort;
mybyte will contain the value 140. Short is a 2-byte type and a byte is a single byte. When you cast from ...
- 483
7
votes
Accepted
sizeof(int) is 2 bytes in some computers, while it is 4 bytes in most modern ones. Why is it so?
This is an excellent question. Understanding this behaviour means knowing a bit about the history of the C language, and the design and development of CPUs.
The short answer is that the size ...
- 2,625
2
votes
Accepted
How does HEAD in linked list work?
Your question is unclear, but I'll take a shot at it. In a linked list, HEAD is usually a var name, not a data type. HEAD is usually a pointer or possibly a data structure that serves as the pointer ...
- 63.4k
2
votes
Accepted
Pset4 error: invalid operands to binary expression ('double' and 'double (*)(void)')
drand48 is a function that takes no arguments and returns a double. It's declared in stdlib.h. You should call it like
drand48();
- 17.4k
1
vote
Accepted
Segmentation fault: Data types for key and entered text by user while program operated through CLI
The program does not validate the number of arguments passed to it, therefore if program is run with none or one argument, it will fail on one of the atoi calls.
From the spec:
If your program is ...
- 26.8k
1
vote
Accepted
Filter - Structures & Headers
The code knows how long each structure element is, thanks to the definition in the header file, so it only needs to add the appropriate number of bytes to the starting address to get to anything. The ...
- 63.4k
1
vote
Accepted
ProblemSet1 - Another Credit.c issue - Can't convert the floating value of my variables into an integer value
Having problems with this?
temp_b /= (10 ^ 14);
That would be because the ^ operator is not an exponent operator as it is in mathematics. It's the exclusive or operator. You might try a call to pow()....
- 63.4k
1
vote
Accepted
datatype string is malfunctioning in pset2 2020
According to the man page, printf returns an int
Return value
Upon successful return, these functions return the number of
characters printed (excluding the null byte used to end output to
...
- 26.8k
1
vote
Accepted
Return type of printf in C
you are right, in fact the printf function return value is as follows:
Return Value On success, the total number of characters written is
returned.
If a writing error occurs, the error ...
- 5,172
1
vote
Accepted
pset1 credit.c – is this a data type conversion error?
int chopoffend(long long n)
int in C is 4 bytes max, that is 2^32 -> 10 digits max
- 1,139
1
vote
Accepted
Limits of data type as explained in Week-1
The problem is how numbers are stored. A computer operates with a binary or base-2 number system. The real world operates in a base-10 system. The only fractional numbers that can be stored with ...
- 63.4k
1
vote
Accepted
Pset4 recover: can't seem to use struct to identify the jpg
You're overthinking this. A struct is not necessary here. Why not try storing your identifiers in an array instead?
- 3,035
1
vote
Accepted
C data types and format specifiers
INT02-C. Understand integer conversion rules
Conversions can occur explicitly as the result of a cast or implicitly
as required by an operation. Although conversions are generally
required ...
- 2,575
1
vote
C data types and format specifiers
Looks like C is (internally) casting the constant 2 (or probably more correctly, the result of n - 2) as an int since that is the essential difference between the two printfs.
You might search the ...
- 26.8k
1
vote
Accepted
Pointers & Integer Arithmetic Question
you loop runs infinitely because num never reduces again when it is less than 9. but you else has problem.
int mod(int *a, int num)
{
if (num/10 > 10)
{
int value = num % 10;
...
- 549
1
vote
Accepted
difference between string, pointer, array and int
i = 32768;
No reason at all why this wouldn't work. First, the size of int is 2^32 at the appliance, not 2^16. Second, even if you enter a higher value, it will never segfault. It will wrap around ...
- 1,677
1
vote
return value of sizeof()
quoting the C99 standard (6.5.3.4 - 20):
C89, like K&R, defined the result of the sizeof operator to be a
constant of an unsigned integer type. Common implementations, and
common usage, ...
- 17.4k
1
vote
Data compression: dictionary encoding
if you assign a unique number to each dictionary entry and the numbers are assigned sequentially, they run from 0 to 24,999, as you said. Now, it's just a matter of converting 24,999 to binary.
If ...
- 63.4k
1
vote
string variable is not working
You don't even need to use string.h header file if you don't need to use string specific functions. Try to use following to figure it out by yourself:
#include <stdio.h>
int main(void)
{
...
- 111
1
vote
string variable is not working
The type string is not a native type in C. It's defined by the CS50 library which you can use by #includeing the cs50.h header file and linking the library's binary file with -lcs50.
The actual type ...
- 17.4k
1
vote
Accepted
Why using variable of double type for storing number of pixels? pset4
The screen width/height is measured in pixels, but the getX and getY can be any floating number. Modern graphics libraries tend to use floating point numbers because you can draw an image "not on a ...
- 18.3k
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