add hex

data/3.C语言高阶/3.位运算/4.十六进制/bin_to_hex.c

+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c & 15];
+  }
+}
+
+int main(int argc, char **argv) {
+  char *str = "HelloWorld!";
+  char *hex = (char *)malloc(512 * sizeof(char));
+  bin_to_hex(str, strlen(str), hex);
+  printf("%s", hex);
+  return 0;
+}
\ No newline at end of file

data/3.C语言高阶/3.位运算/4.十六进制/bin_to_hex.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "bin_to_hex.md"
+}
\ No newline at end of file

data/3.C语言高阶/3.位运算/4.十六进制/bin_to_hex.md

+# 十六进制转换
+
+将任意二进制数据转成16进制并打印hex字符串
+
+## template
+
+```c
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+$code
+
+int main(int argc, char **argv) {
+  char *str = "HelloWorld!";
+  char *hex = (char *)malloc(512 * sizeof(char));
+  bin_to_hex(str, strlen(str), hex);
+  printf("%s", hex);
+  return 0;
+}
+```
+
+## 答案
+
+```c
+void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c & 15];
+  }
+}
+```
+
+## 选项
+
+### 选项1
+
+```c
+void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c << 4];
+  }
+}
+```
+
+### 选项2
+
+```c
+void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c << 4];
+    out[i * 2 + 1] = lut[c & 15];
+  }
+}
+```
+
+### 选项3
+
+```c
+void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c & 16];
+  }
+}
+```
\ No newline at end of file

data/3.C语言高阶/3.位运算/4.十六进制/config.json

@@ -6,5 +6,7 @@
     "C语言"
   ],
   "children": [],
-  "export": []
+  "export": [
+      "bin_to_hex.json"
+  ]
 }
\ No newline at end of file