CODEWITHSUNDEEP
c#filefor-loop
hi itsme
hi itsme

Reputation: 445

Write to a file using a for loop

This is a beginners question but the true is I never needed to use a method like this!
So I´ll need your patience..
I have several strings named t1, t2, t3, t4...and i want to write them to a file, one at each line
so i open the file ..

string t1 = "aaa";
string t2 = "bbb";
string t3 = "ccc";
//10 strings

for (int i = 1; i<= 10; i++)
{
    string key = "t" + i;
    strLine = convertToFile(key);
    f.WriteLine(strLine);
}
f.Close();

Like this all I get in the file is
t1
t2
t3

Upvotes: 0

Views: 318

Answers (5)

AAberdeen
AAberdeen

Reputation: 61

If you are trying to convert a string (from a user input perhaps) to a local variable then you would be better using if or case.

for (int i = 1; i <= 10; i++)
            {
                string key = "t" + i;
                if (key == "t1")
                {
                f.WriteLine(t1);
                }
                else if (key == "t2")
                {
                f.WriteLine(t2);
                }

            }

Or to build on Tim Schmelter's Answer

var t = new List<string>();
        t.Add("aaa");
        t.Add("bbb");
        t.Add("ccc");
        // ...

        using (StreamWriter w = File.AppendText(path))
        {
            for (int i = 1; i <= 10; i++)
            {
                string key = "t"+i;

                if (key == "t1")
                {
                w.WriteLine(t[1]);
                }
                else if (key == "t2")
                {
                    w.WriteLine(t[2]);
                }

            }

        }

Or without the string

            for (int i = 1; i <= 10; i++)
            {
                w.WriteLine(t[i]);
            }

Upvotes: 1

anhoppe
anhoppe

Reputation: 4507

The point is that you cannot access variables in the way your code outlines. What you do in the for loop is constructing the variable name you what to access. But you just generate a string that is named like your variables, but you cannot access them through a string. A variable in C# is a reference, the name you give it does not really matter. So all answers above solve your problem but you should carefully think about the result you expected from your code and why it does not work that way.

Upvotes: 1

Shell
Shell

Reputation: 6849

Simple as that

StringBuilder sb = new StringBuilder();

sb.AppendLine("aaa");
sb.AppendLine("bbb");
sb.AppendLine("ccc");

System.IO.File.WriteAllText("D:\fileName.txt", sb.ToString());

Upvotes: 1

Tim Schmelter
Tim Schmelter

Reputation: 460238

Use a collection instead of single variables:

var allStrings = new List<string>();
allStrings.Add("aaa");
allStrings.Add("bbb");
allStrings.Add("ccc");
// ...

using (StreamWriter w = File.AppendText(path))
{
   foreach(string str in allStrings)
       w.WriteLine(str );
}

or more concise using File.WriteAllLines:

File.WriteAllLines(path, allStrings);

Upvotes: 3

Kamil Budziewski
Kamil Budziewski

Reputation: 23107

better store your strings in List<string> and then use this method:

File.WriteAllLines(filePath, lines);

it will store your list of strings in file at filePath

to create list from your strings do:

var lines = new List<string>{ t1, t2, t3, t4, t5, t6, t7, t8, t9, t10};

Upvotes: 0

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