string - Read For Learn

How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?

Use rfind overload that takes the search position pos parameter, and pass zero for it: Who needs anything else? Pure STL! Many have misread this to mean “search backwards through the whole string looking for the prefix”. That would give the wrong result (e.g. string(“tititito”).rfind(“titi”) returns 2 so when compared against == 0 would return false) and it would be inefficient (looking through … Read more

Python: Converting string into decimal number

If you want the result as the nearest binary floating point number use float: If you want the result stored exactly use Decimal instead of float:

Reading string by char till end of line C/C++

You want to use single quotes: Double quotes (“) are for strings, which are sequences of characters. Single quotes (‘) are for individual characters. However, the end-of-line is represented by the newline character, which is ‘\n’. Note that in both cases, the backslash is not part of the character, but just a way you represent … Read more

Hash function for a string

First, it usually does not matter that much in practice. Most hash functions are “good enough”. But if you really care, you should know that it is a research subject by itself. There are thousand of papers about that. You can still get a PhD today by studying & designing hashing algorithms. Your second hash … Read more

How to interpolate variables in strings in JavaScript, without concatenation?

You can take advantage of Template Literals and use this syntax: Template literals are enclosed by the back-tick (` `) (grave accent) instead of double or single quotes. This feature has been introduced in ES2015 (ES6). Example How neat is that? Bonus: It also allows for multi-line strings in javascript without escaping, which is great for templates: Browser support: … Read more

Allocating string with malloc

malloc() returns a void* pointer to a block of memory stored in the heap. Allocating with malloc() does not initialize any string, only space waiting to be occupied.To add a null-terminating character, you either have to do this yourself, or use a function like scanf(), which adds this character for you. Having said this, you … Read more

How to alphabetically sort strings?

You could use std::set or std::multiset (if you will allow repeated items) of strings, and it will keep the items sorted automatically (you could even change the sorting criteria if you want). input: Gerardo Carlos Kamilo Angel Bosco output:

Pandas error “Can only use .str accessor with string values”

It’s happening because your last column is empty so this becomes converted to NaN: If you slice your range up to the last row then it works: Alternatively you can just select the cols that are object dtype and run the code (skipping the first col as this is the ‘Name’ entry):

C++ – Assigning null to a std::string

I can’t assign a null to a String? No. std::string is not a pointer type; it cannot be made “null.” It cannot represent the absence of a value, which is what a null pointer is used to represent. It can be made empty, by assigning an empty string to it (s = “” or s = std::string()) or by clearing … Read more

Immutable class?

What is an immutable object? An immutable object is one that will not change state after it is instantiated. How to make an object immutable? In general, an immutable object can be made by defining a class which does not have any of its members exposed, and does not have any setters. The following class … Read more

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