利用正则表达式:
参考:http://blog.csdn.net/yangbingzhou/article/details/51352648
#include <regex.h>
char tmpbuf[128] = {0};
char buffer[128] = {0};
char sizebuf[30] = {0};
int ret = 0, res = 0;
int size = 0;
regex_t re;
regmatch_t match[1];
memset(&re, 0, sizeof(re));
res = regcomp(&re, "[0-9]+", REG_EXTENDED);
if (res) {
sprintf(ddr_size, "Unknown");
goto out;
}
ret = regexec(&re, tmpbuf, 1, match, 0);
if (ret == 0 && match[0].rm_so >= 0)
memcpy(sizebuf, &tmpbuf[match[0].rm_so],
(match[0].rm_eo-match[0].rm_so));
size = atoi(sizebuf);
如果是格式已知的字符串, 如 "profile3", 从中提取数字3, 则可以使用函数sscanf, 如下:
char profile[20] = "profile3";
int err, profile_id;
err = sscanf(profile, "profile%d", &profile_id);
参考: https://www.cnblogs.com/lanjianhappy/p/6861728.html
例子: 从文件中提取数字
static int get_isp_bufnum(int width, int height)
{
FILE *f = NULL;
int got = 0;
char *s, tmp_buf[256];
int resv_mem = 0;
int buf_num = 0;
#define RESV_MEM_PATH "/sys/devices/platform/rts_soc_camera/meminfo"
if (width * height <= 1280 * 720)
return 3;
f = fopen(RESV_MEM_PATH, "r");
if (f != NULL) {
while (!got) {
s = fgets(tmp_buf, sizeof(tmp_buf), f);
if (s == NULL)
break;
if (sscanf(tmp_buf, "total : %d", &resv_mem) == 1) {
if (resv_mem >= 32 * 1024 * 1024)
buf_num = 3;
else
buf_num = 2;
got = 1;
pe_log(PM, AV_LOG_INFO, "resv_mem %d\n",
resv_mem);
}
}
fclose(f);
}
if (!got)
buf_num = 2;
return buf_num;
}
long int strtol(const char *nptr,char **endptr,int base);
参数base范围从2至36,或0。参数base代表采用的进制方式,如base值为10则采用10进制,若base值为16则采用16进制等。当base值为0时则是采用10进制做转换,但遇到如’0x’前置字符则会使用16进制做转换、遇到’0’前置字符而不是’0x’的时候会使用8进制做转换。
一开始strtol()会扫描参数nptr字符串,跳过前面的空格字符,直到遇上数字或正负符号才开始做转换,再遇到非数字或字符串结束时('\0')结束转换,并将结果返回。若参数endptr不为NULL,则会将遇到不合条件而终止的nptr中的字符指针由endptr返回;若参数endptr为NULL,则会不返回非法字符串。