Initial commit: C language learning code

翁凯C语言/7/字符串函数strlen.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include <stdbool.h>
+#include <string.h>
+
+// !字符串函数string.h
+/*
+	1.string.h
+	  strlen、strcmp、strcpy、strcat、strchr、strstr
+	2.strlen
+	  size_t strlen(const char *s);
+	  返回s的字符串长度（不包括结尾的0)
+	3.
+*/
+
+int my_strlen(const char *s)
+{
+	int idx = 0;
+	while (s[idx]!='\0')
+	{
+		idx++;
+	}
+	return idx;
+}
+
+int main(void)
+{
+	/* strlen */
+	char line[] = "Hello";
+	printf("strlen=%lu\n", strlen(line));
+	printf("my_strlen=%d\n", my_strlen(line));
+	printf("sizeof=%lu\n", sizeof(line));
+
+	return 0;
+}