C language: Convert 16 binary string to int type value

Converts a 16-binary string value to an int integer value

This example uses "1de" as the test string, the implementation code is as follows:

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2. #include <stdio.h>
4. #include <stdlib.h>
6. #include <string.h>
8. #include <ctype.h>
12. /*
14. * Convert characters to numeric values
16. * */
18. int c2i (char ch)
20. {
22. //If it is a number, subtract 48 from the ASCII code of the number if ch = ' 2 ', then ' 2 '-= 2
24. if (isdigit (CH))
26. return ch-48;
30. //If it is a letter, but not a~f,a~f returns
32. if (Ch < ' A ' | | (Ch > ' F ' && ch < ' a ') | | ch > ' z ')
34. return-1;
38. //If it is an uppercase letter, subtract 55 from the ASCII code of the number if ch = ' A ', then ' a '-= ten
40. //If it is a lowercase letter, subtract 87 from the ASCII code of the number, if ch = ' A ', then ' a '-= ten
42. if (isalpha (CH))
44. return Isupper (CH)? ch-55:ch-87;
48. return-1;
50. }
54. /*
56. * Function: Convert hexadecimal string to integer (int) value
58. * */
60. int Hex2dec (char *hex)
62. {
64. int len;
66. int num = 0;
68. int temp;
70. int bits;
72. int i;
76. //In this example hex = "1de" Length is 3, hex is the main function passed
78. Len = strlen (hex);
82. For (i=0, temp=0; i<len; i++, Temp=0)
84. {
86. ///First time: i=0, * (hex + i) = * (hex + 0) = ' 1 ', i.e. temp = 1
88. ///second time: I=1, * (hex + i) = * (hex + 1) = ' d ', i.e. temp =
90. //Third: i=2, * (hex + i) = * (hex + 2) = ' d ', i.e. temp =
92. temp = c2i (* (hex + i));
94. //Total 3 bits, one 16 binary bit saved with 4 bit
96. ///First: ' 1 ' is the highest bit, so temp shifts left (len-i-1) * 4 = 2 * 4 = 8-bit
98. ///second: ' d ' is a secondary high, so temp shifts left (len-i-1) * 4 = 1 * 4 = 4-bit
100. //Third: ' E ' is the lowest bit, so temp shifts left (len-i-1) * 4 = 0 * 4 = 0-bit
102. Bits = (Len-i-1) * 4;
104. temp = temp << bits;
108. //You can also use num + = temp here;
110. num = num | Temp
112. }
116. //Return results
118. return num;
120. }
126. int main (int argc, char *argv[])
128. {
130. char ch[10] = {0};
132. strcpy (CH, "1de");
134. printf ("hex:%d\n", Hex2dec (CH));
136. return 0;
138. }

I tested at CentOS 6.5

Compilation: Gcc-wall Test.c-ohex

Run:./hex

Output: hex:478

C language: Convert 16 binary string to int type value