go-cheatsheet

postgres

1. Connect

go run postgres/1-connect.go

Hello, world!

gorilla/mux

1. Return a small text message for the /hello path

go run gorillamux/1-newrouter.go

curl localhost:8080/hello

Hello there!

2. Methods function adds a matcher for HTTP methods

Send http.StatusOK for the HEAD method, other methods are not allowed.

go run gorillamux/2-methods.go

curl -I localhost:8080/hello

HTTP/1.1 200 OK

Date: Mon, 22 Apr 2024 13:56:03 GMT

3. Send a name as a query string

go run gorillamux/3-query-params.go

curl localhost:8080/hello?name=John%20Doe

Hello John Doe!

4. Process a name variable from the URL path

go run gorillamux/4-path-vars.go

curl localhost:8080/hello/John%20Doe

Hello John Doe!

5. Determine the current datetime and send it as JSON response

go run gorillamux/5-json-response.go

curl localhost:8080/now

{"now":"Mon Apr 22 14:01:01 2024"}

6. Create two subroutes to organize handlers into logical groups

go run gorillamux/6-subroutes.go

curl localhost:8080/path1/

Subroute 1

curl localhost:8080/path2/

Subroute 2

7. Serve static files from a subdirectory for the app URL path

go run gorillamux/7-static-files.go

curl localhost:8080/app/

This text in "gorillamux/7-static-files/index.html" without HTML-tags.

http/server

1. Each time the URL is visited, a counter is incremented and the value is returned

go run http/server/1-handle.go

curl localhost:8080/count && curl localhost:8080/count && curl localhost:8080/count

Counter: 1

Counter: 2

Counter: 3

2. Create a simple HTTP server listening on port 8080

go run http/server/2-handlefunc.go

curl localhost:8080

Hello, there

3. Send the http.StatusOK for the /status path

go run http/server/3-status-code.go

curl -I localhost:8080/status

HTTP/1.1 200 OK

Date: Tue, 23 Apr 2024 06:00:35 GMT

4. We have three endpoints, for anything other than these three endpoints, we return a 404 error message

go run http/server/4-not-found-handler.go

curl localhost:8080/about && curl localhost:8080 && curl localhost:8080/contact

about page

home page

404 - not found

5. Get the User-Agent header from the Header field and return it back to the caller

go run http/server/5-get-header-server.go

go run http/server/5-get-header-client.go

User agent: Go-http-client/1.1

6. Get the URL path value with r.URL.Path[1:] and build a message with the data

go run http/server/6-path-param.go

curl localhost:8080/John

7. Accept a name parameter and get the parameter with r.URL.Query()["name"]

go run http/server/7-query-param.go

curl localhost:8080/?name=Peter

Hello Peter!

8. A file server and a simple hello handler

go run http/server/8-file-server.go

curl localhost:8080

Home page. This text in "http/server/8-file-server/index.html" without HTML-tags.

curl localhost:8080/about.html

About page. This text in "http/server/8-file-server/about.html" without HTML-tags.

9. Servers processes the GET and the POST requests from a client (no CSRF protection!)

go run http/server/9-get-post.go

See the HTML form located at "http/server/9-get-post/form.html" at the following link: localhost:8080

curl -d 'name=John' -d 'occupation=Teacher' localhost:8080

John is a Teacher

10. Create a simple web server that sends an image to the client

go run http/server/10-serve-image.go

curl -I localhost:8080/image

HTTP/1.1 200 OK

Content-Type: image/png

Date: Tue, 23 Apr 2024 06:35:11 GMT

11. Return an HTML page with a table of users for the /users URL path

go run http/server/11-template.go

See the HTML page with a table of users at the following link: localhost:8080/users

http/client

1. Create a GET request to a small website and get the status code of the request

go run http/client/1-status-code.go

200 OK

200

2. Create a simple GET request and print the received data to the console

go run http/client/2-get-request.go

3. Issue a HEAD request with http.Head and prints all the data of the response header

go run http/client/3-head-request.go

4. Set a User-Agent header for its GET request

go run http/client/4-user-agent-header.go

5. Send a POST request to an online testing website

go run http/client/5-postform.go

json

1. Transform a Go struct and a slice of structs into JSON format

go run json/1-encoding.go

2. Decode a JSON string into a Go struct and a slice of structs

go run json/2-decoding.go

3. Prettify output with MarshalIndent

go run json/3-pretty_print.go

4. Read JSON data from a file and decode it to a slice of user structs

go run json/4-read_file.go

5. Read data from a web service using the built-in Go HTTP client

go run json/5-astros.go

csv

1. Read values from "csv/csv-files/numbers.csv" file

go run csv/1-read.go

2. ReadAll values from "csv/csv-files/users.csv" file

go run csv/2-readall.go

3. Read "csv/csv-files/users-delimiter.csv" where fields are separated with a semicolon

go run csv/3-delimiter.go

4. Write records to "csv/csv-files/users-writed.csv" file

go run csv/4-write.go

5. Append a new record to "csv/csv-files/users-writed.csv" file

go run csv/5-append.go

6. Another example to read values from "csv/csv-files/users.csv" file

go run csv/6-read.go

7. CSV-to-JSON: read "csv/csv-files/users.csv" file and convert its data to JSON

go run csv/7-csv-json.go

Extra 1. Write records to "csv/csv-files/persons-writed.csv" file using "github.com/gocarina/gocsv"

go run csv/extra/1-write-gocsv.go

Extra 2. Read "csv/csv-files/persons-writed.csv" using "github.com/gocarina/gocsv"

go run csv/extra/2-read-gocsv.go

Extra 3. Read "csv/extra/json2csv_input.json" and convert it to "csv/csv-files/json2csv_output.csv" CSV-file using "github.com/yukithm/json2csv"

go run csv/extra/3-json2csv.go

mutexes

Example 1 of the race condition

go run mutexes/1-race-condition.go && go run mutexes/1-race-condition.go && go run mutexes/1-race-condition.go && go run mutexes/1-race-condition.go && go run mutexes/1-race-condition.go

go run mutexes/1-mutex.go && go run mutexes/1-mutex.go && go run mutexes/1-mutex.go && go run mutexes/1-mutex.go && go run mutexes/1-mutex.go

Example 2 of the race condition

go run mutexes/2-race-condition.go && go run mutexes/2-race-condition.go && go run mutexes/2-race-condition.go && go run mutexes/2-race-condition.go && go run mutexes/2-race-condition.go

go run mutexes/2-mutex.go && go run mutexes/2-mutex.go && go run mutexes/2-mutex.go && go run mutexes/2-mutex.go && go run mutexes/2-mutex.go

Concurrent map iteration and map write

go run mutexes/3-concurrent-iter-write.go

go run mutexes/3-mutex.go

go run mutexes/3-rwmutex.go

basic

go run basic/0-basic-program.go

go run basic/1-for-loop.go

go run basic/2-multiple-values-from-func.go

go run basic/3-strings-builder.go

go run basic/4-pointer.go

go run basic/5-type-conversion.go

go run basic/6-copy-map.go

go run basic/7-reverse-int-slice.go

go run basic/8-oop.go

go run basic/9-check-var-type.go

go run basic/10-concatenate-str.go

go run basic/11-func-closures.go

go run basic/12-implement-stack-lifo.go

go run basic/13-slice-chars-permutate.go

go run basic/14-vars-values-swap.go

go run basic/15-min-max.go

go run basic/16-check-slice-is-empty.go

go run basic/17-sum-of-squares.go

go run basic/18-sum-even-from-1-to-100.go

go run basic/19-largest-smallest-in-array.go

go run basic/20-prime-num.go

go run basic/21-factorial-of-num-recursion.go

go run basic/22-num-of-words.go

go run basic/23-bubble-sort.go

go run basic/24-permutations.go

go run basic/25-boyer-moore-search.go

go run basic/26-longest-subsequence-in-array.go

go run basic/27-binary-tree.go

go run basic/28-stack-array.go

go run basic/29-split-strings.go

Sorting a slices of strings and checking whether it is in sorted form or not

go run basic/30-sort-slice-str.go

Sorting a slices of strings by length then alphabetically

go run basic/31-sort-slice-str-len-alphabet.go

Length of shortest string in a slice of strings

go run basic/32-shortest-len.go

An example of how to parse the HTML code

go run basic/33-parse-html-table.go

atomic

Example 1

go run atomic/1-wrong-output.go && go run atomic/1-wrong-output.go && go run atomic/1-wrong-output.go && go run atomic/1-wrong-output.go && go run atomic/1-wrong-output.go

go run atomic/1-correct-output.go && go run atomic/1-correct-output.go && go run atomic/1-correct-output.go && go run atomic/1-correct-output.go && go run atomic/1-correct-output.go

channels

go run channels/1-hello.go

go run channels/2-sum-of-squares.go

go run channels/3-merge-sort.go

problem-list/easy

1. Two sum

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order.

go run problem-list/easy/1-two-sum.go

2. Palindrome number without converting the integer to a string

Given an integer x, return true if x is a palindrome, and false otherwise.

go run problem-list/easy/2-palindrome-no-int2str.go

3. Roman to integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

go run problem-list/easy/3-roman-to-int.go

4. Add two numbers (non-linked lists)

You are given two non-empty lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a list.

Example:

Input: l1 = [2,4,3], l2 = [5,6,4]

Output: [7,0,8]

Explanation: 342 + 465 = 807

go run problem-list/easy/4-add-two-numbers.go