my_atoi

自己实现的atoi函数，包括10进制和16进制：

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#include <stdio.h>#include <stdlib.h>#include <string.h>int my_atoi(const char *str);int main() {char *s = "-10";int n = my_atoi(s);printf("my_atoi result: %d\n", n);return 0;}int my_atoi(const char *str) {int result = 0;int signal = 1;int step = 10;if (!str)return 0;if (!str[0])return 0;if (*str == '-') {signal = -1;str++;}else if (*str == '0' && (*(str + 1) == 'x' || *(str + 1) == 'X')) {step = 16;str += 2;}if (step == 10) {while (*str >= '0' && *str <= '9') {result = result * 10 + (*str - '0');str++;}}else if (step == 16) {while (*str) {if (*str >= '0' && *str <= '9') {result = result * 16 + (*str - '0');}else if (*str >= 'a' && *str <= 'f') {result = result * 16 + (*str - 'a' + 10);}else if (*str >= 'A' && *str <= 'f') {result = result * 16 + (*str - 'A' + 10);}str++;}}return signal * result;}

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