I'm working on a Qt based software that involves some cryptography. The only three hashing algorithms used are specified as 

```
SHA-256
MD5
SHA

```

However, the API that i am using requires them to be in the form of

```
sha256
md5
sha

```

respectively. 
Even though I can write a messy function to somehow get things done, I know this can be simplified with the regular expression support in Qt. Please help me come up with a regular expression that does this task of conversion. 

This is what I am doing now

```
if (hashType == QString("SHA")) {
        return QString("sha");
    }
    else if (hashType == QString("MD5")) {
        return QString("md5");
    }
    else if (hashType == QString("SHA-256")) {
        return QString("sha256");
    }
    else {
        return hashType;
    }

```