Question: ```
def ints(filename):
    a = []
    f = open(filename, "r")
    lines = f.readlines()
    f.close()
    for line in lines:
        numbers = line.split()
        for number in numbers:            
            a.append(int(number))
    return a

```

This is my function so far, I want to be able to read a file containing integers and characters like "x" and "b" etc and return a list of only the integers. At the moment the function can only deal with a file containing integers.

How can I modify this to exclude characters or letters?

Answer: 
I just simply tested if characters were numbers:

```
sample_string = "Test4. 2325This string3"
a_list = []
for x in sample_string:
    if x.isdigit():
        a_list.append(x)

```
```
for number in numbers:
    try:
        a.append(int(number))
    except ValueError:
        pass

```