C + + string converted to floating point type

The first type:

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1. Char szstring[] = "3.1415926535898";
2. Double db1;
3. DB1 = Atof (szstring);
4. printf ("Atof result:\n");
5. printf ("%f%.12f%.2f%e%e\n", DB1, DB1, DB1, DB1, DB1);
6. printf ("%.1e%.1e%.18e%.18e\n", DB1, DB1, DB1, DB1);

The second type:

[CPP]View PlainCopy

1. Char szstring2[] = "3.1415926535898";
2. Double DB2;
3. SSCANF (SzString2, "%lf", &DB2);
4. printf ("\nsscanf result:\n");
5. printf ("%f%.12f%.2f%e%e\n", DB2, DB2, DB2, DB2, DB2);
6. printf ("%.1e%.1e%.18e%.18e\n", DB2, DB2, DB2, DB2);

There are many magical functions for the SSCANF function. Let's look at the use of the encyclopedia:

1. Common usage.

Char buf[512];

SSCANF ("123456", "%s", buf);//Here buf is the name of the array, which means to deposit 123456 in buf in the form of%s!

printf ("%s\n", buf);

The result is: 123456

2. Take a string of the specified length. As in the following example, take a string with a maximum length of 4 bytes.

SSCANF ("123456", "%4s", buf);

printf ("%s\n", buf);

The result is: 1234

3. The string to take to the specified character. As in the following example, the string is encountered until the space is met.

SSCANF ("123456 Abcdedf", "%[^]", buf);

printf ("%s\n", buf);

The result is: 123456

4. Take a string that contains only the specified character set. As in the following example, take a string that contains only 1 to 9 and lowercase letters.

SSCANF ("123456abcdedfBCDEF", "%[1-9a-z]", buf);

printf ("%s\n", buf);

The result is: 123456ABCDEDF

When entering:

SSCANF ("123456abcdedfBCDEF", "%[1-9a-z]", buf);

printf ("%s\n", buf);

The result is: 123456

5. The string to be taken to the specified character set. As in the following example, take a string that encounters an uppercase letter.

SSCANF ("123456abcdedfBCDEF", "%[^a-z]", buf);

printf ("%s\n", buf);

The result is: 123456ABCDEDF

6, given a string iios/[email protected], gets/And the string between @, first filter out "iios/", and then send a string of non-' @ ' to BUF

SSCANF ("Iios/[email protected", "%*[^/]/%[^@]", buf);

printf ("%s\n", buf);

The result is: 12DDWDFF

C + + string converted to floating point type