PHP has made a calculator. if something goes wrong, solve it! -Php Tutorial

PHP has made a calculator. if something goes wrong, solve it! Here is the processing code for making 0 inputs:

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If ($ _ POST ['num0']) {
$ Num = $ _ POST ['num0'];
If (is_dir ('txt ')){
$ Open = fopen ("txt/caculator.txt", "r + ");
If (is_file ("txt/caculator.txt ")){
$ A = file_get_contents ("txt/caculator.txt ");
$ E = (int) $;
$ B = $ e. "0 ";
Echo $ B;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
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This is the form:
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Calculator

If (! Is_dir ('txt ')){
If (! Is_file ("txt/caculator.txt ")){
Echo "success
Caculator2.txt caculator3.txt can complete the task normally! '); Script ";
}}
If ($ _ POST ['num0']) {
$ Num = $ _ POST ['num0'];
If (is_dir ('txt ')){
$ Open = fopen ("txt/caculator.txt", "r + ");
If (is_file ("txt/caculator.txt ")){
$ A = file_get_contents ("txt/caculator.txt ");
$ E = (int) $;
$ B = $ e. "0 ";
Echo $ B;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 1
If ($ _ POST ['num1']) {
$ Num = $ _ POST ['num1'];
If (is_dir ('txt ')){
$ Open = fopen ("txt/caculator.txt", "r + ");
If (is_file ("txt/caculator.txt ")){
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}

If ($ _ POST ['num2']) {
// Click the response of number 2
$ Num2 = $ _ POST ['num2'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num2;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 3
If ($ _ POST ['num3']) {

$ Num = $ _ POST ['num3'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 4
If ($ _ POST ['num4']) {

$ Num = $ _ POST ['num4'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 5
If ($ _ POST ['num5']) {

$ Num = $ _ POST ['num5'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in Number 6
If ($ _ POST ['num6']) {

$ Num = $ _ POST ['num6'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 7
If ($ _ POST ['num7']) {

$ Num = $ _ POST ['num7'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 8
If ($ _ POST ['num8']) {

$ Num = $ _ POST ['num8'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the response in number 9
If ($ _ POST ['num9']) {

$ Num = $ _ POST ['num9'];
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
// Click the reaction of a vertex.
If ($ _ POST ['dot ']) {

$ Num = $ _ POST ['dot '];

If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ Findimethyl = ".";
$ Pos = strpos ($ a, $ findimethyl );
If ($ pos = true ){

File_put_contents ("txt/caculator.txt", $ );
Fclose ($ open );
}
Else {
$ B = $ a. $ num;
File_put_contents ("txt/caculator.txt", $ B );
Fclose ($ open );
}
}
}
}
// Click the response of Option C.
If ($ _ POST ['clear']) {


If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "w + ");
$ Open;
$ Open = fopen ("txt/caculator2.txt", "w + ");
$ Open2;
$ Open = fopen ("txt/caculator3.txt", "w + ");
$ Open3;

}
}
}
// Click response.
If ($ _ POST ['back']) {
If (is_dir ('txt ')){
If (is_file ("txt/caculator.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ A = file_get_contents ("txt/caculator.txt ");
$ A = substr ($ a, 0,-1 );
File_put_contents ("txt/caculator.txt", $ );
}
}
}
// Click + response
If ($ _ POST ['add']) {
If (is_dir ('txt ')){
If (is_file ("txt/caculator2.txt") & is_file ("txt/caculator.txt") & is_file ("txt/caculator3.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ Open2 = fopen ("txt/caculator2.txt", "r + ");
$ Open2;
$ Open3 = fopen ("txt/caculator3.txt", "r + ");
$ Open3;
$ B = "";
$ C = "+ ";
$ A = file_get_contents ("txt/caculator.txt ");
File_put_contents ("txt/caculator.txt", $ B );
File_put_contents ("txt/caculator2.txt", $ );
File_put_contents ("txt/caculator3.txt", $ c );
}
}

}
// Click-response
If ($ _ POST ['sub']) {
If (is_dir ('txt ')){
If (is_file ("txt/caculator2.txt") & is_file ("txt/caculator.txt") & is_file ("txt/caculator3.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ Open2 = fopen ("txt/caculator2.txt", "r + ");
$ Open2;
$ Open3 = fopen ("txt/caculator3.txt", "r + ");
$ Open3;
$ B = "";
$ C = "-";
$ A = file_get_contents ("txt/caculator.txt ");
File_put_contents ("txt/caculator.txt", $ B );
File_put_contents ("txt/caculator2.txt", $ );
File_put_contents ("txt/caculator3.txt", $ c );
}
}

}
// Click the multiplication response.
If ($ _ POST ['mul']) {
If (is_dir ('txt ')){
If (is_file ("txt/caculator2.txt") & is_file ("txt/caculator.txt") & is_file ("txt/caculator3.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ Open2 = fopen ("txt/caculator2.txt", "r + ");
$ Open2;
$ Open3 = fopen ("txt/caculator3.txt", "r + ");
$ Open3;
$ B = "";
$ C = "*";
$ A = file_get_contents ("txt/caculator.txt ");
File_put_contents ("txt/caculator.txt", $ B );
File_put_contents ("txt/caculator2.txt", $ );
File_put_contents ("txt/caculator3.txt", $ c );
}
}

}
// Click the = response
If ($ _ POST ['equal']) {
If (is_dir ('txt ')){
If (is_file ("txt/caculator2.txt") & is_file ("txt/caculator.txt") & is_file ("txt/caculator3.txt ")){
$ Open = fopen ("txt/caculator.txt", "r + ");
$ Open;
$ Open2 = fopen ("txt/caculator2.txt", "r + ");
$ Open2;
$ Open3 = fopen ("txt/caculator3.txt", "r + ");
$ Open3;
$ A = file_get_contents ("txt/caculator.txt ");
$ B = file_get_contents ("txt/caculator2.txt ");
$ C = file_get_contents ("txt/caculator3.txt ");
$ Nul = "";
If ($ c = "+ "){
$ D = $ B + $;
}
If ($ c = "-"){
$ D = $ B-$;
}
If ($ c = "*"){
$ D = $ a * $ B;
}
If ($ c = "/"){
$ D = $ B/$;
}
If ($ c = "% "){
$ D = $ B % $;
}
If ($ c = "+ "){
$ D = $ a + $ B;
}
If ($ c = "√ "){
$ D = sqrt ($ );
}
File_put_contents ("txt/caculator.txt", $ d );

}
}

}

The above are most of the code. due to limited input characters, the key code is pasted out.

There are a lot of code. you should say something went wrong.

Your problem is:
If ($ _ POST ['num0']) {
Because $ _ POST ['num0'] is equal to 0, the constant condition is invalid. This branch will not enter!
Change
If ($ _ POST ['num0'] = '0 '){

Your program design is unreasonable and requires significant adjustments.
Improper use of file operation functions
Since file_get_contents and file_put_contents are used to read and write files, fopen and fclose are not required.
File_put_contents has a FILE_APPEND parameter that can be used to append content to a file without reading it and then manually appending it.

If necessary, you can use the adjusted code for your reference.

Using AJAX, and then dynamic PHP compilation, we can put a lot of companies into computing.

Your problem is:
If ($ _ POST ['num0']) {
Because $ _ POST ['num0'] is equal to 0, the constant condition is invalid. This branch will not enter!
Change
If ($ _ POST ['num0'] = '0 '){

Your program design is unreasonable and requires significant adjustments.
Improper use of file operation functions
Since file_get_contents and file_put_contents are used to read and write files, fope ......
Moderators... I just started learning...
Please give me more advice later!