A standard C function that returns the length of a string.
This function calculates the length of the string, excluding the terminating null byte \0. It is defined in the <string.h> standard header.
Questions tagged [strlen]
692 questions
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votes
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Why is my (re)implementation of strlen wrong?
I came up with this little code but all the professionals said its dangerous and I should not write code like this. Can anyone highlight its vulnerabilities in 'more' details?
int strlen(char *s){
return (*s) ? 1 + strlen(s + 1) : 0;
}
Bálint Juhász
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4
votes
3 answers
How could a PHP value contain a string of zero length not equal to the empty string or null?
I am retrieving some data from an in-house store and in case of failure, I get a very specific response. Calling strlen() on this variable returns the value of zero. It is also not equal to NULL or "". I'm using this code to test:
if ($data ===…
Erick Robertson
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2 answers
For any string "char name[10]="test"",is strlen(name)+1 always guaranteed to be same as sizeof(name)?
For a string name[],can we use strlen(name)+1 and sizeof(name) interchangeably in our code without second thought?Aren't they same?I checked about it and found out even the return type for both is same,size_t.And after all sizeof calculates the size…
Thokchom
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2 answers
Why is absence of array index in "extern char name[]" not affecting strlen(name) but causing error for sizeof(name)?
Now,from what I understand,the extern in the declaration of name[] tells the compiler that its definition is somewhere else (In my program,I have defined it below the part where I have used it).But why then there is different consequence for…
Thokchom
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4
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4 answers
Where C++ really stores a string if the char array that stores it is smaller than a string is?
I'm testing an example about strings in C++ from "C++ Premiere" book.
const int size = 9;
char name1[size];
char name2[size] = "C++owboy"; // 8 characters here
cout << "Howdy! I'm " << name2 << "! What's your name?" << endl;
cin >> name1; // I…
Green
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4 answers
What is the size of a double pointer string?
Assume I have char **argv. How do I determine its size?
I have a string - an example would be: sleep 30 & that is held in argv. I would like to be able to access the last array in *argv. In this case, the last array contains &. How can I access it?…
darksky
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3 answers
How to strlen of a multi-language string
I want to get strlen() of Shift-jis and Utf-8, then compare them.
A string could be mixed "ああ12345678sdfdszzz". I tried to use strlen but it generates the different results. mb_strlen also doesn't help because this is a mixed string.
For…
emeraldhieu
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3
votes
3 answers
PHP - strlen not working
In Register.php, it contains a form.
3
votes
1 answer
static size_t strnlen(const char *s, size_t max) -- why a static return value?
I might be going insane, but I don't think I've ever seen this in c++ (though my reference code is in C). Why is there a static on the return value of the code here and what impact does it have? I don't think I've ever seen a static function…
John Humphreys
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3 answers
Why is the param of strlen a "const"?
I'm learning the C language.
My question is:
Why is the param of strlen a "const" ?
size_t strlen(const char * string);
I'm thinking it's because string is an address so it doesn't change after initialization. If this is right, does that mean every…
conradkleinespel
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3
votes
7 answers
substr with strlen
I have an amount like 0003000, the last 2 digits are the decimal number. I want to transform 0003000 to 00030,00 (insert a decimal comma in front of the last 2 digits).
I tried to do this with substring. I take the length of the string with strlen…
Markey
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votes
2 answers
Why are variables of type size_t casted to (unsigned) in a printf call?
I was writing a program and looking up strlen() function on this website http://www.cplusplus.com/reference/cstring/strlen/. I saw that in the example where the function was used, the author of the code put (unsigned) to cast the result of the…
Damian Kowalski
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1 answer
How to traverse a string in assembly until I reach null? (strlen loop)
Right now I'm just figuring out how to even traverse a string. If the code doesn't make sense, it's because I've interpreted some information wrong. At the worst, I don't really know what I'm doing.
strlen:
pushq %rbx
movq %rsi, %rbx
loop:
…
Block o Butter
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- 7
3
votes
7 answers
Different ways to calculate string length
A comment on one of my answers has left me a little puzzled. When trying to compute how much memory is needed to concat two strings to a new block of memory, it was said that using snprintf was preferred over strlen, as shown below:
size_t length =…
user142162
3
votes
3 answers
How to strlen first two parts of an array?
I have an array like,
$words = array ('This', 'is', 'a', '', '', '', 'string');
and I was looking for a function that counts characters of the first two parts,
in this case, this and is should be counted . the result for these two will be 5. I…
Hadi Ahmadi
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