May 12, at pm UTC.
Have been looking at structs, arrays, pointers, maps, templates, vectors, and sets. I am completely lost on how to getline from a user and convert that to an integer pointer that points to a character array of item descriptions from a struct. I'm trying to create a text based game. I have looked at multiple books and through all the Cplusplus tutorials.
I do not want to have endless arrays pointing to endless arrays, as my final program hopefullywill have many items. I am aware that the below code does not compile. Any help will be appreciated, thanks.
May 13, at am UTC. Furthermore, you overthink this You want to just enter a number n and get the item on index n, right? Just save it as int and access the n-th element of itemarray. Last edited on May 13, at am UTC. Gamer Your code is missing either using namespace std; or assorted std:: qualifiers. And itemarray isn't the same as Itemarray And the item extraction is not checked to see if it was valid, nor is the index obtained checked to see if it's in range.
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I have found this in a web site. However, it doesn't work even I change itoa to atoi including stdlib. Nov 14 ' Post Reply. Share this Question. Christopher Benson-Manica. Hint: strtol does it better. Flames welcome. Mike Wahler. An integer type cannot be portably converted to a pointer.
Perhaps you want to create the textual representation of an integer, e. Which shows the danger of looking to 'a web site' for accurate information. You should have at least one preferably two or more books for learning C. See www. The C standard library does have a function 'atoi ', but it converts a the textual representation of an integer to an integer. You won't get far by just guessing and changing things blindly, hoping it will work.
Al Bowers. This discussion thread is closed Start new discussion. Similar topics convert single char to string Error in program. Question stats viewed: replies: 4 date asked: Nov 14 '05 Follow this discussion.Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. This rule applies to both signed char and plain char characters on implementations where char is defined to have the same range, representation, and behaviors as signed char.
This rule is a generalization of STRC. Arguments to character-handling functions must be representable as an unsigned char. This noncompliant code example is taken from a vulnerability in bash versions 1. As characters are retrieved from this pointer, they are stored in a variable of type int.
For implementations in which the char type is defined to have the same range, representation, and behavior as signed charthis value is sign-extended when assigned to the int variable. This example, however, violates STRC. Use plain char for characters in the basic character set.
Do not form or use out-of-bounds pointers or array subscripts :. This compliant solution casts the value of type char to unsigned char before the implicit promotion to a larger type:. Can detect violations of this rule when checking for violations of INTC. Use only explicitly signed or unsigned char type for numeric values. There shall be no implicit conversions from integral to floating type Cast characters to unsigned char before assignment to larger integer sizes An expressions of the 'signed char' type should not be used as an array index Cast characters to unsigned char before converting to larger integer sizes Avoid implicit conversions from floating to integral type A cast should not be performed between a pointer to object type and a different pointer to object type.
Polyspace Bug Finder. CVE results from a violation of this rule. In Linux PAM up to version 1. Search for vulnerabilities resulting from the violation of this rule on the CERT website. The way it's phrased this rule would lead one to believe that casting a char value to any unsigned type before converting it to a larger signed type will prevent sign extension.
In fact, to prevent sign extension, a char value must be cast to unsigned char.C Programming. We know that a string is a sequence of characters which we save in an array. In the following example we are creating a string str using char character array of size 6.
The variable name of the string str holds the address of the first element of the array i. So, we can create a character pointer ptr and store the address of the string str variable in it. This way, ptr will point at the string str. In the following code we are assigning the address of the string str to the pointer ptr. The pointer variable ptr is allocated memory address and it holds the address of the string variable str i. In the following example we are using while loop to print the characters of the string variable str.
We can achieve the same result by creating a character pointer that points at a string value stored at some memory location. In the following example we are using character pointer variable strPtr to store string value. In the above code we are using another character pointer t to print the characters of the string as because we don't want to lose the starting address of the string "Hello" which is saved in pointer variable strPtr. The pointer variable strPtr is at memory location and is pointing at the string address The temporary variable is also assigned the address of the string so, it too holds the value and points at the starting memory location of the string "Hello".
C - Pointers and Strings
In the above code we are creating an array of character pointer cityPtr of size 4 to store the name of the four cities. The cityPtr pointer variable is allocated the memory address to Assuming integer address value takes 2 bytes space. So, each pointer gets 2 bytes. To access and print the values pointed by the array of pointers we take help of loop as shown in the following example.Introduction to pointers in C/C++
In the above code we are using the r variable to access each row of the pointer. And we are using the c variable to access each character in a selected row.
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Pseudo Code.Forum Beginners casting char pointer to unsigned int. Pages: 1 2.
Jun 23, at pm UTC. I thought sizeof allocates enough space so that the object may fit. First, Please use the code tags when posting code. Last edited on Jun 23, at pm UTC. This is extracting the value of one of the four bytes of the unsigned int Close : This code is modifying one of the bytes in A, at offset B to become value C.
And returning the value. So not modifying the original A as it was never passed in by reference. Zaita, Sorry for not posting in code tags, I will take care of it from now on. As for byte and bit manipulation, I would like to get a hang of it by looking at functions that are of bit and byte manipulation nature, it may seem odd, but I am perhaps just a wee bit curious?
I would really appreciate if some insight would be given on this function. Thanks again for your help. Does it mean one off or something else? I'm glad I came across this forum. Thanks again. Offset is which byte, treating the int like a char array the offset is the array index. When we think of an unsigned int, we think of a 4 byte value that looks like 0x When it's stored in memory it looks like 0x Backwards to how we'd think about it.
The return value would be 0x This to us is 0x10 The initial 1 we put in as a is over-written by 0x An offset can be regarded as an adjustment value. It is a term often used with pointers and arrays, as you often take a base pointer value or pointer to an array and an offset to access the elements of the array.
Edit: Clicked submit to see 2 other answers appear - all slightly different, hope one of them explanis it for youIt allocates 12 consecutive bytes for string literal "Hello World" and 4 extra bytes for pointer variable ptr. And assigns the address of the string literal to ptr. So, in this case, a total of 16 bytes are allocated. We already learned that name of the array is a constant pointer. This means string assignment is not valid for strings defined as arrays.
On the contrary, ptr is a pointer variable of type charso it can take any other address. As a result string, assignments are valid for pointers.
After the above assignment, ptr points to the address of "Yellow World" which is stored somewhere in the memory.
We can assign a new string to arr by using getsscanfstrcpy or by assigning characters one by one. Recall that modifying a string literal causes undefined behavior, so the following operations are invalid. Here ptr is uninitialized an contains garbage value. So the following operations are invalid. Now all the operations mentioned above are valid. Another way we can use ptr is by allocation memory dynamically using malloc or calloc functions.
Poniter is used to point address of its data type like int pointer will point to intiger data type and char pointer will point to char data type. Is this character pointer declaration correct? Very good article! Notify me of new posts by email.
In this chapter, we will study the difference between character array and character pointer. Consider the following example:. Enter number of characters to store : 6. Printing elements of 1 - D array :.
Character Array and Character Pointer in C
Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I want to do write code where a pointer is set to a specific memory address, for example 0x If I do the same outside the line of variable declaration, the message is the same but says "assignment" instead of "initialization":. No, it is not valid C and have never been valid C.
These examples are so-called constraint violation of the standard. You need to manually force a type conversion with a cast:.
C - Pointers and Strings
If you don't use the cast, the code is not valid C and your compiler is not allowed to let the code pass without displaying a message. Specifically, this is regulated by the rules of simple assignmentC17 6. Neither of these fit in with any of the constraints cited above. The left operand is a pointer and the right is a null pointer constant. More info about the difference between null pointers, null pointer constants and the NULL macro.
Converting a pointer to an integer is by no means guaranteed to work even with the cast. The standard C17 6. An integer may be converted to any pointer type. Except as previously specified, the result is implementation-defined, might not be correctly aligned, might not point to an entity of the referenced type, and might be a trap representation. Any pointer type may be converted to an integer type.
Except as previously specified, the result is implementation-defined. If the result cannot be represented in the integer type, the behavior is undefined. The result need not be in the range of values of any integer type. In addition, the address from a pointer might be larger than what will fit inside an intas is the case for most 64 bit systems. Learn more. Asked 1 year, 7 months ago.
Active 1 year, 7 months ago. Viewed times. Question: Are the above examples valid C? Lundin Lundin k 19 19 gold badges silver badges bronze badges. AnttiHaapala Yeah good call, especially since the answer already hinted of best practices when dealing with memory addresses.