How to convert a Python string into its escaped version in C++?
Question
I'm trying to write a Python program that reads in a file and prints the contents as a single string as it would be escaped in a C++ format. This is because the string will be copied from Python output and pasted into a C++ program (C++ string variable definition).
Basically, I want to convert
<!DOCTYPE html>
<html>
<style>
.card{
max-width: 400px;
min-height: 250px;
background: #02b875;
padding: 30px;
box-sizing: border-box;
color: #FFF;
margin:20px;
box-shadow: 0px 2px 18px -4px rgba(0,0,0,0.75);
}
</style>
<body>
<div class="card">
<h4>The ESP32 Update web page without refresh</h4><br>
<h1>Sensor Value:<span id="ADCValue">0</span></h1><br>
</div>
</body>
<script>
setInterval(function() {
// Call a function repetatively with 0.1 Second interval
getData();
}, 100); //100mSeconds update rate
function getData() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("ADCValue").innerHTML =
this.responseText;
}
};
xhttp.open("GET", "readADC", true);
xhttp.send();
}
</script>
</html>
to this
<!DOCTYPE html>\n<html>\n<style>\n.card{\n max-width: 400px;\n min-height: 250px;\n background: #02b875;\n padding: 30px;\n box-sizing: border-box;\n color: #FFF;\n margin:20px;\n box-shadow: 0px 2px 18px -4px rgba(0,0,0,0.75);\n}\n</style>\n\n<body>\n<div class=\"card\">\n <h4>The ESP32 Update web page without refresh</h4><br>\n <h1>Sensor Value:<span id=\"ADCValue\">0</span></h1><br>\n</div>\n</body>\n\n<script>\nsetInterval(function() {\n // Call a function repetatively with 0.1 Second interval\n getData();\n}, 100); //100mSeconds update rate\n\nfunction getData() {\n var xhttp = new XMLHttpRequest();\n xhttp.onreadystatechange = function() {\n if (this.readyState == 4 && this.status == 200) {\n document.getElementById(\"ADCValue\").innerHTML =\n this.responseText;\n }\n };\n xhttp.open(\"GET\", \"readADC\", true);\n xhttp.send();\n}\n</script>\n</html>
Using this Python program:
if __name__ == '__main__':
with open(<filepath>) as html:
contents = html.read().replace('"', r'\"')
print(contents)
print('')
print(repr(contents))
I get exactly what I want minus double backslashes when "escaping" the double quotes. I've tried a few random things, but all the attempts either get rid of both backslashes or don't change the string at all.
I simply want to add a single backslash before all the double quotes in my string. Is this even possible in Python?
1 answers
solution1
1 ACCPTED 2020-02-09 06:39:27
You can use str.translate to map the troublesome characters to their escaped equivalents. Since python's rules on escape and quote characters can be a bit baroque, I've just brute forced them for consistency.
# escapes for C literal strings
_c_str_trans = str.maketrans({"\n": "\\n", "\"":"\\\"", "\\":"\\\\"})
if __name__ == '__main__':
with open(<filepath>) as html:
contents = html.read().translate(_c_str_trans)
print(contents)
print('')
print(repr(contents))
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