string matrix into single string

[code]Ok, so i have to convert this matrix into a single line of characters. For example: If i enter {XXXYYY}, i convert it into a matrix {XXX}{YYY}. i need to change it back so i can add another element to the end of the string XXXYYYY and convert it again into a matrix, without showing the first element of it like {XXY}{YYY}. How do i do that?

Code:

for(i=0;i<size;i++)
            {
                aminoacidos[x][y]=nucleotideos[i];
                y++;
                if (y==3)
                {
                    y=0;
                    x++;    
                }
            }
            for (i=0; i<((size)/3); i++) {
                printf("%s\n",aminoacidos[i]);
            }
            if (nucleotideos[size-1]=='a') 
            {
                strcat(nucleotideos, "a");
            }
            if (nucleotideos[size-1]=='t') 
            {
                strcat(nucleotideos, "t");
            }
            if (nucleotideos[size-1]=='c') 
            {
                strcat(nucleotideos, "c");            
            }
            if (nucleotideos[size-1]=='g') 
            {
                strcat(nucleotideos, "g");        
            }
            for(i=1;i<size+1;i++)
            {
                aminoacidos[x][y]=nucleotideos[i];
                y++;
                if (y==3)
                {
                    y=0;
                    x++;    
                }
            }
            for (i=1; i<((size+1)/3); i++) {
                printf("%s\n",aminoacidos[i]);
            }

In a one dim array, matrix elements are accessed like this matrix[ x * cols + y]. If you make a copy of the matrix entering elements with this formula it will work.