atoi的实现
#include <stdio.h> #include <stdlib.h> #define MAX_SIZE 1024 int my_atoi(const char *src) { int result = 0; int flag = 1; if (src == NULL || *src == '\0') { return 0; } if (*src == '-' || *src == '+') { flag = (*src == '-') ? -1 : 1; src++; } while (*src != '\0') { if (*src >= '0' && *src <= '9') { result = result * 10 + (*src - '0'); } else { break; } src++; } return result * flag; } int main(int argc, char **argv) { char src[MAX_SIZE]; printf("请输入一段字符串: \n"); scanf("%s", src); int result = my_atoi(src); printf("%d\n", result); return 0; }
