C/C++: Converting hexadecimal value in char to integer
I have hexadecimal values stored as characters:
char A = \'0\';
char B = \'6\';
char C = \'E\';
... I need them coverted to integers. I kno
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I had a similar problem, but mine involved also verifying that it was a valid Hexidecimal character. Below is my solution that converts from hex char to a binary nibble. (Note: You may want to change uint8_t to int).
The benefit of this approach is that instead of individually checking each character against a lookup table. There is only up to 6 comparison (aside from the null pointer guard) before it can output the answer.
/**----------------------------------------------------------------------------- @brief Converts Hexidecimal Char Value Into Binary Nibble Format Converts 0-9 & a-f & A-F Hex notation to binary nibble between 0x00 to 0x0F Return: True if valid nibble is avaliable at nibble_out else it returns false ------------------------------------------------------------------------------*/ bool char_to_nibble(const char ch, uint8_t *nibble_out) { /* Assumes char ch is encoded in ascii */ if (!nibble_out) { /* Output Pointer Cannot Be Null */ return false; } if ( '0' <= ch && ch <= '9' ) { /* Integer Character */ *nibble_out = ch - '0'; return true; } if ( 'a' <= ch && ch <= 'f' ) { /* Lowercase Letter Character */ *nibble_out = ch - 'a' + 10; return true; } if ( 'A' <= ch && ch <= 'F' ) { /* Upper Case Character */ *nibble_out = ch - 'A' + 10; return true; } return false; }The above function is confirmed to be functional. Proof in test program below.
Test Program
This program demonstrates char_to_nibble() and it's usage.
/******************************************************************************* Parse Hexidecimal Char to binary Nibble ( In C Language ) Brian Khuu 2017 *******************************************************************************/ // Tip: tcc -run ${This File} #include <stdint.h> // Standard Integer (e.g. uint8_t ) #include <stdbool.h> // Standard Boolean #include <stdio.h> // printf() #include <ctype.h> // isprint() #include <stdio.h> // sscanf() /**----------------------------------------------------------------------------- @brief Converts Hexidecimal Char Value Into Binary Nibble Format Converts 0-9 & a-f & A-F Hex notation to binary nibble between 0x00 to 0x0F Return: True if valid nibble is avaliable at nibble_out else it returns false ------------------------------------------------------------------------------*/ bool char_to_nibble(const char ch, uint8_t *nibble_out) { /* Assumes char ch is encoded in ascii */ if (!nibble_out) { /* Output Pointer Cannot Be Null */ return false; } if ( '0' <= ch && ch <= '9' ) { /* Integer Character */ *nibble_out = ch - '0'; return true; } if ( 'a' <= ch && ch <= 'f' ) { /* Lowercase Letter Character */ *nibble_out = ch - 'a' + 10; return true; } if ( 'A' <= ch && ch <= 'F' ) { /* Upper Case Character */ *nibble_out = ch - 'A' + 10; return true; } return false; } /******************************************************************************* Demonstration of char_to_nibble() ******************************************************************************* - Running this program without an argument will spit out the full table. - Running this program with one char per argument will run a partial test. */ void test(const char ch) { /* Runs a test on this char and display the result */ uint8_t nibble = 0; /* Function Under Test */ bool result = char_to_nibble(ch, &nibble); /* Print Result */ printf("| 0x%02X, `%c` | %2u | %s |\r\n", (uint8_t) ch, (isprint(ch)?ch:' '), nibble, (result?"**TRUE**":" FALSE ") ); } #define ARGTOINT(arg, var) if((argc-1) >= arg){sscanf(argv[arg], "%d", &var);} int main(int argc, char *argv[]) { printf("| Input | Output | Is Hex? |\r\n"); printf("|-----------|--------|----------|\r\n"); if (argc == 1) { /* self test on no param */ for (uint16_t i = 0 ; i < 256 ; i++) test((char)i); return 0; } for (int i = 1 ; i < argc ; i++) { /* Process user input (e.g. "a b c d e ..." )*/ char ch = *(argv[i]); test(ch); } return 0; }Full Table Output
This table was generated by running the above test program (empty arg mode). This demonstrates that this function is working as expected.
| Input | Output | Is Hex? | |-----------|--------|----------| | 0x00, ` ` | 0 | FALSE | | 0x01, ` ` | 0 | FALSE | | 0x02, ` ` | 0 | FALSE | | 0x03, ` ` | 0 | FALSE | | 0x04, ` ` | 0 | FALSE | | 0x05, ` ` | 0 | FALSE | | 0x06, ` ` | 0 | FALSE | | 0x07, ` ` | 0 | FALSE | | 0x08, ` ` | 0 | FALSE | | 0x09, ` ` | 0 | FALSE | | 0x0A, ` ` | 0 | FALSE | | 0x0B, ` ` | 0 | FALSE | | 0x0C, ` ` | 0 | FALSE | | 0x0D, ` ` | 0 | FALSE | | 0x0E, ` ` | 0 | FALSE | | 0x0F, ` ` | 0 | FALSE | | 0x10, ` ` | 0 | FALSE | | 0x11, ` ` | 0 | FALSE | | 0x12, ` ` | 0 | FALSE | | 0x13, ` ` | 0 | FALSE | | 0x14, ` ` | 0 | FALSE | | 0x15, ` ` | 0 | FALSE | | 0x16, ` ` | 0 | FALSE | | 0x17, ` ` | 0 | FALSE | | 0x18, ` ` | 0 | FALSE | | 0x19, ` ` | 0 | FALSE | | 0x1A, ` ` | 0 | FALSE | | 0x1B, ` ` | 0 | FALSE | | 0x1C, ` ` | 0 | FALSE | | 0x1D, ` ` | 0 | FALSE | | 0x1E, ` ` | 0 | FALSE | | 0x1F, ` ` | 0 | FALSE | | 0x20, ` ` | 0 | FALSE | | 0x21, `!` | 0 | FALSE | | 0x22, `"` | 0 | FALSE | | 0x23, `#` | 0 | FALSE | | 0x24, `$` | 0 | FALSE | | 0x25, `%` | 0 | FALSE | | 0x26, `&` | 0 | FALSE | | 0x27, `'` | 0 | FALSE | | 0x28, `(` | 0 | FALSE | | 0x29, `)` | 0 | FALSE | | 0x2A, `*` | 0 | FALSE | | 0x2B, `+` | 0 | FALSE | | 0x2C, `,` | 0 | FALSE | | 0x2D, `-` | 0 | FALSE | | 0x2E, `.` | 0 | FALSE | | 0x2F, `/` | 0 | FALSE | | 0x30, `0` | 0 | **TRUE** | | 0x31, `1` | 1 | **TRUE** | | 0x32, `2` | 2 | **TRUE** | | 0x33, `3` | 3 | **TRUE** | | 0x34, `4` | 4 | **TRUE** | | 0x35, `5` | 5 | **TRUE** | | 0x36, `6` | 6 | **TRUE** | | 0x37, `7` | 7 | **TRUE** | | 0x38, `8` | 8 | **TRUE** | | 0x39, `9` | 9 | **TRUE** | | 0x3A, `:` | 0 | FALSE | | 0x3B, `;` | 0 | FALSE | | 0x3C, `<` | 0 | FALSE | | 0x3D, `=` | 0 | FALSE | | 0x3E, `>` | 0 | FALSE | | 0x3F, `?` | 0 | FALSE | | 0x40, `@` | 0 | FALSE | | 0x41, `A` | 10 | **TRUE** | | 0x42, `B` | 11 | **TRUE** | | 0x43, `C` | 12 | **TRUE** | | 0x44, `D` | 13 | **TRUE** | | 0x45, `E` | 14 | **TRUE** | | 0x46, `F` | 15 | **TRUE** | | 0x47, `G` | 0 | FALSE | | 0x48, `H` | 0 | FALSE | | 0x49, `I` | 0 | FALSE | | 0x4A, `J` | 0 | FALSE | | 0x4B, `K` | 0 | FALSE | | 0x4C, `L` | 0 | FALSE | | 0x4D, `M` | 0 | FALSE | | 0x4E, `N` | 0 | FALSE | | 0x4F, `O` | 0 | FALSE | | 0x50, `P` | 0 | FALSE | | 0x51, `Q` | 0 | FALSE | | 0x52, `R` | 0 | FALSE | | 0x53, `S` | 0 | FALSE | | 0x54, `T` | 0 | FALSE | | 0x55, `U` | 0 | FALSE | | 0x56, `V` | 0 | FALSE | | 0x57, `W` | 0 | FALSE | | 0x58, `X` | 0 | FALSE | | 0x59, `Y` | 0 | FALSE | | 0x5A, `Z` | 0 | FALSE | | 0x5B, `[` | 0 | FALSE | | 0x5C, `\` | 0 | FALSE | | 0x5D, `]` | 0 | FALSE | | 0x5E, `^` | 0 | FALSE | | 0x5F, `_` | 0 | FALSE | | 0x60, ``` | 0 | FALSE | | 0x61, `a` | 10 | **TRUE** | | 0x62, `b` | 11 | **TRUE** | | 0x63, `c` | 12 | **TRUE** | | 0x64, `d` | 13 | **TRUE** | | 0x65, `e` | 14 | **TRUE** | | 0x66, `f` | 15 | **TRUE** | | 0x67, `g` | 0 | FALSE | | 0x68, `h` | 0 | FALSE | | 0x69, `i` | 0 | FALSE | | 0x6A, `j` | 0 | FALSE | | 0x6B, `k` | 0 | FALSE | | 0x6C, `l` | 0 | FALSE | | 0x6D, `m` | 0 | FALSE | | 0x6E, `n` | 0 | FALSE | | 0x6F, `o` | 0 | FALSE | | 0x70, `p` | 0 | FALSE | | 0x71, `q` | 0 | FALSE | | 0x72, `r` | 0 | FALSE | | 0x73, `s` | 0 | FALSE | | 0x74, `t` | 0 | FALSE | | 0x75, `u` | 0 | FALSE | | 0x76, `v` | 0 | FALSE | | 0x77, `w` | 0 | FALSE | | 0x78, `x` | 0 | FALSE | | 0x79, `y` | 0 | FALSE | | 0x7A, `z` | 0 | FALSE | | 0x7B, `{` | 0 | FALSE | | 0x7C, `|` | 0 | FALSE | | 0x7D, `}` | 0 | FALSE | | 0x7E, `~` | 0 | FALSE | | 0x7F, ` ` | 0 | FALSE | | 0x80, ` ` | 0 | FALSE | | 0x81, ` ` | 0 | FALSE | | 0x82, ` ` | 0 | FALSE | | 0x83, ` ` | 0 | FALSE | | 0x84, ` ` | 0 | FALSE | | 0x85, ` ` | 0 | FALSE | | 0x86, ` ` | 0 | FALSE | | 0x87, ` ` | 0 | FALSE | | 0x88, ` ` | 0 | FALSE | | 0x89, ` ` | 0 | FALSE | | 0x8A, ` ` | 0 | FALSE | | 0x8B, ` ` | 0 | FALSE | | 0x8C, ` ` | 0 | FALSE | | 0x8D, ` ` | 0 | FALSE | | 0x8E, ` ` | 0 | FALSE | | 0x8F, ` ` | 0 | FALSE | | 0x90, ` ` | 0 | FALSE | | 0x91, ` ` | 0 | FALSE | | 0x92, ` ` | 0 | FALSE | | 0x93, ` ` | 0 | FALSE | | 0x94, ` ` | 0 | FALSE | | 0x95, ` ` | 0 | FALSE | | 0x96, ` ` | 0 | FALSE | | 0x97, ` ` | 0 | FALSE | | 0x98, ` ` | 0 | FALSE | | 0x99, ` ` | 0 | FALSE | | 0x9A, ` ` | 0 | FALSE | | 0x9B, ` ` | 0 | FALSE | | 0x9C, ` ` | 0 | FALSE | | 0x9D, ` ` | 0 | FALSE | | 0x9E, ` ` | 0 | FALSE | | 0x9F, ` ` | 0 | FALSE | | 0xA0, ` ` | 0 | FALSE | | 0xA1, ` ` | 0 | FALSE | | 0xA2, ` ` | 0 | FALSE | | 0xA3, ` ` | 0 | FALSE | | 0xA4, ` ` | 0 | FALSE | | 0xA5, ` ` | 0 | FALSE | | 0xA6, ` ` | 0 | FALSE | | 0xA7, ` ` | 0 | FALSE | | 0xA8, ` ` | 0 | FALSE | | 0xA9, ` ` | 0 | FALSE | | 0xAA, ` ` | 0 | FALSE | | 0xAB, ` ` | 0 | FALSE | | 0xAC, ` ` | 0 | FALSE | | 0xAD, ` ` | 0 | FALSE | | 0xAE, ` ` | 0 | FALSE | | 0xAF, ` ` | 0 | FALSE | | 0xB0, ` ` | 0 | FALSE | | 0xB1, ` ` | 0 | FALSE | | 0xB2, ` ` | 0 | FALSE | | 0xB3, ` ` | 0 | FALSE | | 0xB4, ` ` | 0 | FALSE | | 0xB5, ` ` | 0 | FALSE | | 0xB6, ` ` | 0 | FALSE | | 0xB7, ` ` | 0 | FALSE | | 0xB8, ` ` | 0 | FALSE | | 0xB9, ` ` | 0 | FALSE | | 0xBA, ` ` | 0 | FALSE | | 0xBB, ` ` | 0 | FALSE | | 0xBC, ` ` | 0 | FALSE | | 0xBD, ` ` | 0 | FALSE | | 0xBE, ` ` | 0 | FALSE | | 0xBF, ` ` | 0 | FALSE | | 0xC0, ` ` | 0 | FALSE | | 0xC1, ` ` | 0 | FALSE | | 0xC2, ` ` | 0 | FALSE | | 0xC3, ` ` | 0 | FALSE | | 0xC4, ` ` | 0 | FALSE | | 0xC5, ` ` | 0 | FALSE | | 0xC6, ` ` | 0 | FALSE | | 0xC7, ` ` | 0 | FALSE | | 0xC8, ` ` | 0 | FALSE | | 0xC9, ` ` | 0 | FALSE | | 0xCA, ` ` | 0 | FALSE | | 0xCB, ` ` | 0 | FALSE | | 0xCC, ` ` | 0 | FALSE | | 0xCD, ` ` | 0 | FALSE | | 0xCE, ` ` | 0 | FALSE | | 0xCF, ` ` | 0 | FALSE | | 0xD0, ` ` | 0 | FALSE | | 0xD1, ` ` | 0 | FALSE | | 0xD2, ` ` | 0 | FALSE | | 0xD3, ` ` | 0 | FALSE | | 0xD4, ` ` | 0 | FALSE | | 0xD5, ` ` | 0 | FALSE | | 0xD6, ` ` | 0 | FALSE | | 0xD7, ` ` | 0 | FALSE | | 0xD8, ` ` | 0 | FALSE | | 0xD9, ` ` | 0 | FALSE | | 0xDA, ` ` | 0 | FALSE | | 0xDB, ` ` | 0 | FALSE | | 0xDC, ` ` | 0 | FALSE | | 0xDD, ` ` | 0 | FALSE | | 0xDE, ` ` | 0 | FALSE | | 0xDF, ` ` | 0 | FALSE | | 0xE0, ` ` | 0 | FALSE | | 0xE1, ` ` | 0 | FALSE | | 0xE2, ` ` | 0 | FALSE | | 0xE3, ` ` | 0 | FALSE | | 0xE4, ` ` | 0 | FALSE | | 0xE5, ` ` | 0 | FALSE | | 0xE6, ` ` | 0 | FALSE | | 0xE7, ` ` | 0 | FALSE | | 0xE8, ` ` | 0 | FALSE | | 0xE9, ` ` | 0 | FALSE | | 0xEA, ` ` | 0 | FALSE | | 0xEB, ` ` | 0 | FALSE | | 0xEC, ` ` | 0 | FALSE | | 0xED, ` ` | 0 | FALSE | | 0xEE, ` ` | 0 | FALSE | | 0xEF, ` ` | 0 | FALSE | | 0xF0, ` ` | 0 | FALSE | | 0xF1, ` ` | 0 | FALSE | | 0xF2, ` ` | 0 | FALSE | | 0xF3, ` ` | 0 | FALSE | | 0xF4, ` ` | 0 | FALSE | | 0xF5, ` ` | 0 | FALSE | | 0xF6, ` ` | 0 | FALSE | | 0xF7, ` ` | 0 | FALSE | | 0xF8, ` ` | 0 | FALSE | | 0xF9, ` ` | 0 | FALSE | | 0xFA, ` ` | 0 | FALSE | | 0xFB, ` ` | 0 | FALSE | | 0xFC, ` ` | 0 | FALSE | | 0xFD, ` ` | 0 | FALSE | | 0xFE, ` ` | 0 | FALSE | | 0xFF, ` ` | 0 | FALSE |讨论(0)
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