可以使用strncpy()來將復制字符串中前n個字符。比如：
char str1[] = "this is a string";
char str2[3];
strncpy(str2, str1, 2);
str2[2] = '\0'; // 此時str2="th"

#include <stdio.h>

/**
*** dest - 目標buff
*** src - 源數據
*** len - 獲取源數據左邊的數據個數
**/
char *getLeftX(char *dest, const char *src, unsigned int len) {
sprintf(dest, "%.*s", len, src);
return dest;
}

int main() {
char arr[] = "kalsdfjalsuqiowernalkfasf";
char arr2[256];
int i;

for (i=1; i<sizeof(arr); ++i)
puts(getLeftX(arr2, arr, i));

}

只能是自己寫,
char str[]="this is a string";

char ch1 = str[0];
char ch2 = str[1];

或者
char *p = str;
char ch1 = *p;
p++;
char ch2 = *p