stringbuilder or stringbuffer in MQL4

[jackee1234]

Is there something like a stringbuilder (Java) or stringbuffer (C#) in MQL4 that facilitates fast string append?

[Carl Schreiber]

StringConcatenate()

StringFormat()

StringAdd()

Just type them into the editor place the cursor above one and press F1 to get the details to use them.

[JC]

jackee1234:
Is there something like a stringbuilder (Java) or stringbuffer (C#) in MQL4 that facilitates fast string append?

Not as such, no. There's nothing which defers the creation of a large contiguous memory block into a single final operation, instead of building the string incrementally - no string-builder class, and no alternative such as creating an array of strings and then doing a join operation on it.

However, StringAdd() is vastly faster than StringConcatenate(), and has performance broadly in line with what you'd expect from a string-builder.

[JC]

JC:

However, StringAdd() is vastly faster than StringConcatenate(), and has performance broadly in line with what you'd expect from a string-builder.

... A wrapper such as the following around StringAdd() does improve the performance on large strings compared to a simple repeated concatenation:

class StringBuilder {
   private:
      string large;
      string small;

      void Collapse() {
         StringAdd(large, small);
         small = "";      
      }      
   
   public:
      int _STRING_CONCAT_THRESHOLD;
      
      StringBuilder() {
         large = "";
         small = "";
         _STRING_CONCAT_THRESHOLD = 100000;
      }

      void Append(string X) {
         if (StringLen(X) > _STRING_CONCAT_THRESHOLD) {
            Collapse();
            StringAdd(large, X);
         } else {
            StringAdd(small, X);
            if (StringLen(small) > _STRING_CONCAT_THRESHOLD) {
               Collapse();
            }            
         }
      }
      
      string ToString() {
         Collapse();
         return large;
      }   
};