AP_RangeFinder: use single precision string to float

libraries/AP_RangeFinder/AP_RangeFinder_LightWareSerial.cpp

@@ -67,7 +67,7 @@ bool AP_RangeFinder_LightWareSerial::get_reading(uint16_t &reading_cm)
         char c = uart->read();
         if (c == '\r') {
             linebuf[linebuf_len] = 0;
-            const float dist = (float)atof(linebuf);
+            const float dist = strtof(linebuf, NULL);
             if (!is_negative(dist)) {
                 sum += dist;
                 valid_count++;

libraries/AP_RangeFinder/AP_RangeFinder_NMEA.cpp

@@ -170,12 +170,12 @@ bool AP_RangeFinder_NMEA::decode_latest_term()
     if (_sentence_type == SONAR_DBT) {
         // parse DBT messages
         if (_term_number == 3) {
-            _distance_m = atof(_term);
+            _distance_m = strtof(_term, NULL);
         }
     } else if (_sentence_type == SONAR_DPT) {
         // parse DPT messages
         if (_term_number == 1) {
-            _distance_m = atof(_term);
+            _distance_m = strtof(_term, NULL);
         }
     }
 

libraries/AP_RangeFinder/AP_RangeFinder_Wasp.cpp

@@ -108,7 +108,7 @@ bool AP_RangeFinder_Wasp::get_reading(uint16_t &reading_cm) {
             if (isalpha(linebuf[0])) {
                 parse_response();
             } else {
-                float read_value = (float)atof(linebuf);
+                float read_value = strtof(linebuf, NULL);
                 if (read_value > 0) {
                     sum += read_value;
                     count++;