str to int, long, float; 数字 转 字符串; 大小写转换等

#include

#include
#include
#include
int main(){
	char *str = "-1111.11";
/**
 * 	double atof(const char *nptr);
 *	int atoi(const char *nptr);
 *	long atol(const char *nptr);
 *	long long atoll(const char *nptr);
 */
	printf("atof(%s) = %f\n", str, atof(str));
	printf("atoi(%s) = %d\n", str, atoi(str));
	printf("atol(%s) = %ld\n", str, atol(str));
	printf("atoll(%s) = %lld\n", str, atoll(str));
	puts("================");

	/**
	 *  double strtod(const char *nptr, char **endptr);
	 *	float strtof(const char *nptr, char **endptr);
	 *	long int strtol(const char *nptr, char **endptr, int base);
	 *	unsigned long int strtoul(const char *nptr, char **endptr, int base);
	 */
	printf("strtod(%s, NULL) = %f\n", str, strtod(str, NULL));
	printf("strtof(%s, NULL) = %f\n", str, strtof(str, NULL));
	printf("strtol(%s, NULL, 0) = %ld\n", str, strtol(str, NULL, 0));
	printf("strtol(%s, NULL, 2) = %ld\n", str, strtol(str, NULL, 2));
	printf("strtol(%s, NULL, 16) = %ld\n", str, strtol(str, NULL, 16));
	printf("strtoul(%s, NULL, 0) = %ld\n", str, strtoul(str, NULL, 0));
	puts("================");
//	int sscanf(const char *str, const char *format, ...);
	float value;
	sscanf(str, "%f", &value);
	printf("scanf(\"%s\", \%%f, &value); value = %f\n",  str, value);
	puts("================");
	//==================================================
	double number = -1234.5678;
	int decpt;
	int sign;
/**
 * 	char *ecvt(double number, int ndigits, int *decpt, int *sign);
 *	char *fcvt(double number, int ndigits, int *decpt, int *sign);
 *	char *gcvt(double number, size_t ndigit, char *buf);
 *	These  functions  are  obsolete.  Instead, sprintf() is recommended.
 */
	//when using ecvt and fcvf, the sign and . are removed in the returned string
	// the sign and . are represented by *sign and &decpt
	char *result_str = ecvt(number, 6, &decpt, &sign);
	printf("ecvt: decpt = %d, sign = %d, result_str = %s\n", decpt, sign, result_str);

	char *rt_str = fcvt(number, 6, &decpt, &sign);
	printf("fcvt: decpt = %d, sign = %d, result_str = %s\n", decpt, sign, rt_str);

	char buf[15];
	char *g_str = gcvt(number, 10, buf);
	printf("gcvt, buf = %s,  g_str = %s\n", buf, g_str);
//	 int sprintf(char *str, const char *format, ...);
	char num_str[13];
	sprintf(num_str, "%f", number);
	puts(num_str);
	//======================================
//	int toascii(int c);
	printf("toascii(%c) = %d\n", 'A', toascii('A'));
	printf("toascii(%c) = %d\n", 'a', toascii('a'));
	//======================================
//	int toupper(int c);
//	int tolower(int c);
	char str_k[] = "ab&%CD*#eF";
	int i;
	for(i = 0; i < strlen(str_k); i++)
		str_k[i] = toupper(str_k[i]);
	puts(str_k);

	for(i = 0; i < strlen(str_k); i++)
		str_k[i] = tolower(str_k[i]);
	puts(str_k);
	return 0;
}