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Operating Strings

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NetTradeX Advisors

Operating Strings

Operators for working with strings

Operator	Description
=	String assignment
+	Concatenation of strings
==	Checking strings for equality
!=	Checking strings for inequality
<, >, <=, >=	String comparisons
[]	Access to the elements of string by the index

Example. Printing all letters in a string one by one.

int Initialize()
{
	return(0);
}
int Run()
{
	string a = "NetTradeX";
	for (uint i=0;i<a.length;i++)
	{
		System.Print(""+int8(a[i]));
	}
	return(0);
}
int DeInitialize()
{
	return(0);
}

Strings operating methods

Method	Description
uint length() const	Length of a string
void resize(uint)	Changing the length of a string
bool isEmpty() const	Verification that the string is empty
string substr(uint start = 0, int count = -1) const;	Returning a substring starting from the position `start` with the length of `count` symbols.
int findFirst(const string &in str, uint start = 0) const;	Finding the first occurrence of a substring `str` , starting from `start` position.
int findLast(const string &in str, int start = -1) const;	Finding the last occurrence of a substring `str` not further than `start` symbols from the beginning.
array@ split(const string &in delimiter) const;	Splitting a string into substrings that are recorded in an array.

Example of operating string methods:

int Initialize()
{
	return(0);
}
int Run()
{
	string a = "Hello, NetTradex Advisor!";
	System.Print("Substring = "+a.substr(3,10)); // Output: Substring = lo, NetTra
	System.Print("Find substring \"tT\" pos = "+a.findFirst("tT",1)); // Output: Find substring "tT" pos = 9
	System.Print("Find last = "+a.findLast("o",6)); // Output: Find last = 4
	array<string>words = a.split(" ");
	for(uint i=0;i<words.length();i++)
	{
		System.Print(words[i]);
	}
    System.Print("Joined="+join(words," "));
    return 0;
}
int DeInitialize()
{
	return(0);
}

Strings functions

Function name	Description
string join(const array &in arr, const string &in delimiter);	Putting together elements of an array `arr` using the delimiter, specified in `delimiter` variable.
int64 parseInt(const string &in, uint base = 10, uint &out byteCount = 0)	Converting a string to an int64 variable
double parseFloat(const string &in, uint &out byteCount = 0)	Converting a string to a double variable
string formatInt(int64 val, const string &in options, uint width = 0)	Converting int64 variable to a string using the specified format ^*.
string formatFloat(double val, const string &in options, uint width = 0, uint precision = 0)	Converting double variable to a string using the specified format^*.

^* Strings format specification flags

l - left-align
0 - add zeros on the left
+ - add + for positive numbers
Space - add a space from the left for positive numbers
h - use lowercase letters for hexadecimal numbers
H - use capital letters for hexadecimal numbers
e - use the lowercase "e" for the exponent
E - use the capital "E" for the exponent

Example 1. Demonstrating the use of formatInt and formatFloat functions:

int Initialize()
{
	return(0);
}
int Run()
{
	System.Print(""+formatInt(1245,"0+", 10)); // выведется +000001245
	System.Print(""+formatInt(0xAbCd,"lH", 10)); // выведется ABCD
	System.Print(""+formatFloat(1234567,"E",10,4)); // 1.2346E+006
	return(0);
}
int DeInitialize()
{
	return(0);
}

Example 2. Conversion a string into a number:

int Initialize()
{
	return(0);
}
int Run()
{
	uint a;
	System.Print(""+parseInt("12345678",10,a));
	System.Print("a="+a);
	return(0);
}
int DeInitialize()
{
	return(0);
}