Concatenating string and integer in Python
Modern string formatting: “{} and {}”.format(“string”, 1)
concatenation
R – Concatenate two dataframes?
You want “rbind”. b$b <- NA new <- rbind(a, b) rbind requires the data frames to have the same columns. The first line adds column b to data frame b. Results > a <- data.frame(a=c(0,1,2), b=c(3,4,5), c=c(6,7,8)) > a a b c 1 0 3 6 2 1 4 7 3 2 5 8 > … Read more
Best way to concatenate vectors in Rust
The structure std::vec::Vec has method append(): fn append(&mut self, other: &mut Vec<T>) Moves all the elements of other into Self, leaving other empty. From your example, the following code will concatenate two vectors by mutating a and b: fn main() { let mut a = vec![1, 2, 3]; let mut b = vec![4, 5, 6]; … Read more
How do I combine two lists in Dart?
You can use: var newList = new List.from(list1)..addAll(list2); If you have several lists you can use: var newList = [list1, list2, list3].expand((x) => x).toList() As of Dart 2 you can now use +: var newList = list1 + list2 + list3; As of Dart 2.3 you can use the spread operator: var newList = […list1, … Read more
How can I concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
Standard C Preprocessor $ cat xx.c #define VARIABLE 3 #define PASTER(x,y) x ## _ ## y #define EVALUATOR(x,y) PASTER(x,y) #define NAME(fun) EVALUATOR(fun, VARIABLE) extern void NAME(mine)(char *x); $ gcc -E xx.c # 1 “xx.c” # 1 “<built-in>” # 1 “<command-line>” # 1 “xx.c” extern void mine_3(char *x); $ Two levels of indirection In a comment … Read more
How do I concatenate multiple C++ strings on one line?
#include <sstream> #include <string> std::stringstream ss; ss << “Hello, world, ” << myInt << niceToSeeYouString; std::string s = ss.str(); Take a look at this Guru Of The Week article from Herb Sutter: The String Formatters of Manor Farm
Concatenating null strings in Java [duplicate]
Why must it work? The JLS 5, Section 15.18.1.1 JLS 8 § 15.18.1 “String Concatenation Operator +”, leading to JLS 8, § 5.1.11 “String Conversion”, requires this operation to succeed without failure: …Now only reference values need to be considered. If the reference is null, it is converted to the string “null” (four ASCII characters … Read more
Most efficient way to concatenate strings in JavaScript?
Seems based on benchmarks at JSPerf that using += is the fastest method, though not necessarily in every browser. For building strings in the DOM, it seems to be better to concatenate the string first and then add to the DOM, rather then iteratively add it to the dom. You should benchmark your own case … Read more
SQL UPDATE all values in a field with appended string CONCAT not working
That’s pretty much all you need: mysql> select * from t; +——+——-+ | id | data | +——+——-+ | 1 | max | | 2 | linda | | 3 | sam | | 4 | henry | +——+——-+ 4 rows in set (0.02 sec) mysql> update t set data=concat(data, ‘a’); Query OK, 4 rows … Read more
Include constant in string without concatenating
No. With Strings, there is no way for PHP to tell string data apart from constant identifiers. This goes for any of the string formats in PHP, including heredoc. constant() is an alternative way to get hold of a constant, but a function call can’t be put into a string without concatenation either. Manual on … Read more